EN： The present perfect tense (has/have + past participle) is used here with 'left' (though expressed as simple past 'left' in casual speech, it implies a present result). 'Left' is the past tense of 'leave', meaning to allow something to remain in a place.
中文： 动词“leave”（留下/遗忘）的过去式为“left”。在这里使用一般过去时“left”来描述过去发生的动作（把包留在这里），而这个动作的结果（包还在这里）对现在造成了影响。
I left my keys on the kitchen table.
我把钥匙留在厨房桌上了。
EN： The interrogative pronoun 'Whose' is used to ask about possession. In the question 'Whose can it be?', 'whose' acts as a possessive pronoun meaning 'whose bag', and 'can' is a modal verb used to express possibility or speculation.
中文： 疑问代词“Whose”（谁的）用来询问物品的所有权。在“Whose can it be?”这个问句中，“whose”作为所有格代词，代表“谁的包”，而助动词“can”则用于表示对可能性的推测或怀疑。
Whose is this jacket?
这件夹克是谁的？
EN： The modal verb 'might' is used to express a weak possibility or uncertainty about a present or future situation. It suggests that something is possible, but not certain.
中文： 情态助动词 'might' 用于表示对现在或未来情况的微弱可能性或不确定性。它暗示某事是有可能的，但并不确定。
It might rain later, so you should take an umbrella.
等一下可能会下雨，所以你该带把伞。
EN： The phrasal verb 'belong to' means to be the property of someone. It is a stative verb, meaning it is not typically used in the continuous (-ing) tenses.
中文： 短语动词 'belong to' 意思是“属于某人（的财产）”。它是一个状态动词，这意味着它通常不适用于进行时（-ing）。
This book belongs to Sarah.
这本书是莎拉的。
EN： The modal verb 'can't' (cannot) is used to express a strong negative deduction or certainty based on evidence. It means 'it is impossible that...'.
中文： 情态助动词 'can't'（cannot）用于表示基于证据的强烈否定推论或确定性，意思是“不可能……”。
It can't be raining; the sky is completely clear.
不可能在下雨；天空完全是晴朗的。
EN： Possessive pronouns (such as 'mine', 'yours', 'his', 'hers', 'ours', 'theirs') are used to replace a possessive adjective and a noun to avoid repetition. Here, 'mine' replaces 'my bag'.
中文： 所有格代词（如 'mine'、'yours'、'his' 等）用来代替“形容词性物主代词 + 名词”以避免重复。在此句中，'mine' 代替了 'my bag'（我的包）。
Your car is red, but mine is green.
你的车是红色的，但我的（车）是绿色的。
EN： The modal verb 'must' is used here to express a strong logical deduction or certainty based on evidence. It translates to '一定' (must be) in this context.
中文： 情态助动词“must”在此处用于表示基于证据的强烈逻辑推论或肯定。在这种语境下，它翻译为“一定”。
She must be tired after working all day.
工作了一整天，她一定累了。
EN： The preposition 'with' is used to indicate the cause or reason for a state (in this case, being heavy). It means '因為...' or '伴隨著...'.
中文： 介词“with”在此处用于表示某种状态（在此指“很重”）的原因或伴随情况。意思是“因为……”或“装着……”。
His hands were shaking with cold.
他的手因为冷而发抖。
EN： The modal verb 'could' is used here to express a weak or tentative possibility in the present. It suggests that something is possible, but the speaker is not entirely certain.
中文： 情态动词“could”在此处用于表示现在时间里较为微弱或不确定的可能性。它表示某事是有可能的，但说话者并非百分之百确定。
The keys could be in your coat pocket.
钥匙可能在你的外套口袋里。
EN： The prepositional phrase 'in the library' acts as an adverbial of place, indicating the location of the subject. It consists of the preposition 'in' followed by the noun phrase 'the library'.
中文： 介词短语“in the library”作为地点状语短语，用来指示主语所在的地点。它由介词“in”和名词短语“the library”组成。
The students are studying in the library.
学生们正在图书馆里学习。
EN： The modal structure 'might have + past participle' is used to express a weak or uncertain possibility about a past event. It suggests that something possibly happened, but the speaker is not entirely sure.
中文： 助动词结构“might have + 过去分词（p.p.）”用于表示对过去事件的微弱或不确定推测。这意味着某事在过去有可能发生，但说话者并不完全确定。
He might have missed the bus this morning.
他今天早上可能错过公交车了。
EN： The preposition 'after' is used here as a preposition of time, meaning 'subsequent to' or 'later than' a specific event (in this case, 'class').
中文： 介词“after”在此处用作时间介词，意思是“在...之后”，表示在某个特定事件（在此处为“下课”）之后发生的时间点。
We went for a walk after dinner.
我们晚餐后去散步了。
EN： The modal verb 'can't' (cannot) is used to express a strong negative deduction or certainty. When we say 'it can't be...', we are 99% sure that something is impossible based on present evidence.
中文： 情态助动词 'can't'（cannot）用于表示强烈的否定推论或确定性。当我们说 'it can't be...' 时，代表我们根据目前的证据，有极高的把握（约99%）认为某事是不可能的。
It can't be raining; the sky is completely clear.
不可能在下雨；天空完全是晴朗的。
EN： The verb 'hear' is a verb of perception. It can be followed directly by an object ('something') and an adverbial of place ('inside') to describe what is being perceived and where.
中文： 动词 'hear'（听见）是一个感官动词。后面可以直接接宾语（'something'，某物）和地点副词（'inside'，在里面），用来描述所感知到的事物及其位置。
I hear a strange noise outside.
我听到外面有奇怪的声音。
EN： The modal verb 'must' is used here to express a strong logical deduction or certainty based on evidence. It translates to 'must be' or 'definitely is' in this context.
中文： 情态动词“must”在此处用于表示基于证据的强烈逻辑推论或肯定（一定、必定）。
The lights are on, so they must be home.
灯亮着，所以他们一定在家。
EN： The present participle (verb-ing) 'rattling' acts as an object complement, describing the action or state of the noun 'water bottle' at the moment of perception.
中文： 现在分词（动词-ing）“rattling”在此作为宾语补足语，用来描述名词“water bottle”在被察觉时的动作或状态（正在发出咔嗒声）。
I can hear the rain falling on the roof.
我能听到雨水落在屋顶上的声音。
EN： The modal verb 'may' is used to express possibility or uncertainty in the present or future. It suggests that something is possible but not certain (about a 50% chance). It is followed by the base form of the verb.
中文： 情态助动词“may”用于表示现在或未来“可能性”或“不确定性”。它表示某事有可能发生但并不完全确定（大约有50%的几率）。其后必须接动词原形。
It may rain later, so you should take an umbrella.
等一下可能会下雨，所以你该带把伞。
EN： The verb 'give' is a ditransitive verb, which means it can take two objects: an indirect object (usually a person, here 'us') and a direct object (usually a thing, here 'a clue'). The typical pattern is 'give + indirect object + direct object'.
中文： 动词“give”（给）是双宾语动词（授与动词），这意味着它可以接两个宾语：间接宾语（通常是人，此处为“us”）和直接宾语（通常是物，此处为“a clue”）。常见句型为“give + 间接宾语 + 直接宾语”。
She gave me a beautiful book.
她给了我一本书。
EN： The modal verb 'could' is used here to express a weak or tentative possibility in the present or future, meaning 'it is possible that'. It is less certain than 'may' or 'must'.
中文： 情态助动词 'could' 在此处用于表示现在或未来较弱或不确定的可能性，意思是“有可能”。它的肯定程度低于 'may' 或 'must'。
It could rain later, so you should take an umbrella.
待会儿可能会下雨，所以你该带把伞。
EN： The phrasal verb 'belong to' means to be the property of someone. It is a non-progressive (stative) verb, meaning it is not typically used in the continuous (-ing) tenses.
中文： 短语动词 'belong to' 意思是“属于某人（的财产）”。它是一个静态动词，通常不用于进行时（-ing 形式）。
This bicycle belongs to my brother.
这辆自行车是我弟弟的。
EN： The modal verb 'must' combined with the continuous aspect 'be + -ing' (must be doing) is used to express a strong, logical deduction about an action that is likely happening right now. It indicates that the speaker is almost certain about the current activity based on evidence.
中文： 情态动词“must”结合进行式“be + -ing”（must be doing）用于对此时此刻正在发生的动作进行强烈的逻辑推测。这表示说话者根据现有的线索，对目前正在进行的活动感到几乎可以确定。
She must be sleeping now because her room is completely dark.
她现在一定正在睡觉，因为她的房间完全是暗的。
EN： The phrasal verb 'look for' means to search for something or someone. When used with a pronoun object like 'it', the pronoun must be placed directly after the preposition 'for' (look for it).
中文： 短语动词“look for”意思是寻找某物或某人。当与代词宾格（如“it”）连用时，该代词必须直接放在介词“for”后面（写成 look for it）。
I lost my keys and I am looking for them.
我弄丢了钥匙，我正在寻找它们。
EN： The structure 'Let's + base verb' is used to make a suggestion or proposal that includes the speaker. It is a contraction of 'Let us'.
中文： 「Let's + 动词原形」结构用于提出包含说话者在内的建议或提议。它是「Let us」的缩写形式。
Let's start the meeting now.
我们现在开始开会吧。
EN： Tag questions with 'Let's' typically use 'shall we?' to politely ask for agreement or confirmation, making the suggestion sound softer and more cooperative.
中文： 以“Let's”开头的祈使句，其附加疑问句通常使用“shall we?”，用于礼貌地寻求对方的同意或确认，使建议听起来更温和且具合作意图。
Let's go for a walk, shall we?
我们去散个步，好吗？
EN： In British and Commonwealth English, 'shall we?' is a very common and natural way to end a suggestion starting with 'Let's'. In American English, it is also widely used, though sometimes 'okay?' or 'should we?' might be heard in more casual contexts. Using 'shall we?' adds a touch of politeness and collaborative spirit.
中文： 在英式英語與大英國協國家中，以「shall we?」作為「Let's」開頭建議的結尾是非常普遍且自然的用法。在美式英語中也相當常見，儘管在更口語的非正式情境中，人們有時會用「okay?」或「should we?」。使用「shall we?」能增添一種禮貌與共同參與的溫和語氣。
EN： The Simple Past Tense is used to describe actions that were completed at a specific time in the past. In this sentence, 'found' is the irregular past tense form of the verb 'find'.
中文： 一般过去时（Simple Past Tense）用于描述在过去特定时间已经完成的动作。在本句中，“found”是动词“find”的不规则过去式变化。
Yesterday I found a lost wallet on the street.
昨天我在街上发现了一个遗失的钱包。
EN： Time expressions like 'this morning' can function as adverbial modifiers. They are often placed at the very beginning or the very end of a sentence to establish the timeframe of the event.
中文： 像“this morning”（今天早上）这样的时间副词短语，常用于修饰整个句子。它们通常放在句首或句尾，用来建立事件发生的时间背景。
This morning she drank a cup of black coffee.
今天早上她喝了一杯黑咖啡。
EN： The coordinating conjunction 'so' is used to connect two independent clauses, showing a cause-and-effect relationship where the second clause is the result of the first.
中文： 对等连接词「so」（所以）用于连接两个独立从句，表示因果关系，第二个从句为第一个从句所产生的结果。
It was raining, so we stayed indoors.
下雨了，所以我们待在室内。
EN： An indirect question is used inside another sentence (here, as the object of 'wondered'). Unlike direct questions, indirect questions use statement word order (subject + verb) instead of question word order.
中文： 间接问句用于另一个句子中（在此作为动词“wondered”的宾语/宾语）。与直接问句不同，间接问句使用陈述句语序（主语 + 动词），而非疑问句语序。在此“who”同时作为主语，因此后面直接接动词“wrote”。
I wondered where she lived.
我想知道她住在哪里。
EN： The coordinating conjunction 'so' is used to connect two independent clauses, showing a cause-and-effect relationship where the second clause is the result of the first.
中文： 对等连接词「so」（所以）用于连接两个独立从句，表示因果关系，第二个从句为第一个从句所产生的结果。
The weather was bad, so we stayed indoors.
天气很糟糕，所以我们待在室内。
EN： The modal verb 'might' is used to express weak possibility or uncertainty about a present or future situation, followed by the base form of the verb 'be'.
中文： 情态助动词“might”（可能）用于表示对现在或未来情况较微弱的可能性或不确定推测，后接动词原形“be”。
It is cloudy, so it might rain later.
天阴阴的，所以等一下可能会下雨。
EN： The modal verb 'couldn't' is used to express a strong negative deduction or impossibility in the past or present based on evidence.
中文： 情态助动词 'couldn't' 用于根据现有证据，对过去或现在的事情做出强烈的否定推测或表示“不可能”。
It couldn't be Ryan's jacket; his is much larger.
那不可能是莱恩的外套；他的尺寸大得多。
EN： The subordinating conjunction 'because' is used to introduce a clause that gives the reason for the action or state in the main clause.
中文： 从属连词 'because'（因为）用于引导原因从句，解释主句动作或状态发生的原因。
Sarah was late because she missed the bus.
莎拉迟到了，因为她没赶上公交车。
EN： In English-speaking school cultures, communication between teachers and students is often polite but can be relatively informal. However, 'casual' language (like slang or highly informal text-speak) is still generally avoided by teachers in official or written contexts, which is why the speaker deduces the note wasn't written by a teacher.
中文： 在英語系國家的校園文化中，師生之間的交流雖然客氣，但有時相對隨和。然而，教師在書面或正式場合通常仍會避免使用過於「隨性」（casual）的語言（如俚語或過度簡化的網路用語），這也是為什麼說話者會推斷這張紙條不可能是老師寫的。
EN： The modal verb 'must' is used here to express a strong logical assumption or high probability based on evidence. It translates to '一定...' (must be) in this context.
中文： 情态助动词“must”在此处用于表示基于证据的强烈逻辑推测或高度可能性。在这种语境下，它翻译为“一定...”。
She must be tired after the long trip.
经过长途旅行后，她一定累了。
EN： The relative pronoun 'who' introduces a defining relative clause ('who knows my schedule well') that modifies the noun 'someone'. It acts as the subject of the relative clause.
中文： 关系代词“who”引导一个限定修饰名词“someone”的关系从句（who knows my schedule well）。它在关系从句中担任主语的角色。
I am looking for a teacher who speaks English fluently.
我正在寻找一位英语说得很流利的老师。
EN： The verb 'say' is commonly used in English to report written text, signs, or messages, where in Chinese we would typically translate it as '寫著' (written) or '寫到' (says/reads).
中文： 动词“say”（说）在英语中常用来表达书面文字、告示或消息的内容，在中文里通常会被翻译为“写着”或“写到”，而不是“说”。
The sign says 'No Parking'.
告示牌上写着「禁止停车」。
EN： The modal verb 'can' is used here to express ability or possibility. In the encouraging phrase 'You can do it!', it serves to motivate someone by emphasizing their capability to succeed.
中文： 情态动词“can”在此处用于表示能力或可能性。在鼓励的话语“You can do it!”（你做得到的！）中，它通过强调某人的能力来达到激励的效果。
I believe you can pass the driving test.
我相信你能够通过路考。
EN： In English-speaking school culture, it is very common for friends, classmates, or teachers to leave small encouraging notes (sometimes called 'sticky notes' or 'cheer cards') on someone's desk before a major exam or sports event to boost their morale.
中文： 在英語系國家的學校文化中，在重大考試或體育賽事之前，朋友、同學或老師很流行在彼此的書桌上留下鼓勵的小紙條（有時是便利貼或加油卡），藉此幫對方加油打氣。
EN： The modal verb 'might' is used to express weak possibility or uncertainty about a present or future situation. It is followed by the base form of the verb (in this case, 'be').
中文： 情态动词“might”用于表示对现在或未来状况较弱的可能性或不确定性。其后接动词原形（在此句中为“be”）。
It might rain later, so you should take an umbrella.
等一下可能会下雨，所以你该带把伞。
EN： Present participle phrases (verb-ing) can function as adjectives to modify a preceding noun. Here, 'sitting near me' is a participle phrase modifying the noun 'classmate', describing an ongoing state or action.
中文： 现在分词短语（动词-ing）可作为形容词，用来修饰前面的名词。在此处，“sitting near me”是一个分词短语，修饰名词“classmate”（同班同学），描述其当下的状态或动作。
The girl standing by the door is my sister.
站在门旁边的那个女孩是我姐姐。
EN： The modal verb 'could' is used here to express a weak or uncertain possibility in the present. It suggests that something is possible, but the speaker is not entirely sure.
中文： 情态助动词“could”在此处用于表示现在时间里较微弱或不确定的“可能性”。它表示某事是有可能的，但说话者并非百分之百确定。
It could rain later, so you should take an umbrella.
待会儿可能会下雨，所以你该带把伞。
EN： The conjunction 'since' is used to introduce a clause that gives the reason for something, functioning similarly to 'because' or 'as'.
中文： 从属连词“since”在此处用于引导表示“原因”的从属从句，功能类似于“because”（因为）或“as”（由于）。
Since we have some free time, let's grab a cup of coffee.
既然我们有些空闲时间，我们去喝杯咖啡吧。
EN： The phrasal verb 'cheer someone on' is a common expression in English-speaking cultures, reflecting a supportive and encouraging social dynamic. It is often used in both sports contexts and everyday life to show emotional support for someone's efforts.
中文： 片語動詞「cheer someone on」（為某人加油打氣）在英語系國家是非常常見的表達方式，反映了人際關係中互相支持與鼓勵的社交文化。它不僅常用於體育賽事中，也廣泛用於日常生活中，表示對他人付出的努力給予情感上的支持。
EN： The compound relative pronoun 'whoever' is used here to introduce an adverbial clause meaning 'no matter who'. It indicates that the identity of the person does not change the main fact.
中文： 复合关系代词“whoever”在此处引导一个让步状语从句，表示“不论是谁、不管是是谁”。这说明该人物的具体身份并不会改变主句所描述的事实。
Whoever made this cake is a great baker.
不论是谁做了这个蛋糕，他都是个很棒的烘焙师。
EN： The modal structure 'must have + past participle' is used to express a strong logical deduction or certainty about a past event.
中文： 情态动词结构“must have + 过去分词（p.p.）”用于对过去发生的事情进行强烈的逻辑推测或肯定推断，表示“过去一定、想必已经……”。
She must have left her keys at the office.
她一定是把钥匙忘在办公室了。
EN： The modal verb 'can' is used here to express theoretical possibility or general truth, indicating that even small actions have the potential to produce a significant impact.
中文： 情态助动词“can”在此处用于表示理论上的可能性或普遍真理，指出即使是微小的行动也有可能产生重大的影响。
Regular exercise can improve your health.
规律的运动可以改善你的健康。
EN： The phrase 'mean so much' uses the verb 'mean' (to have importance or value) modified by 'so much' (to a great degree) to express deep emotional significance or value.
中文： 短语“mean so much”使用动词“mean”（具有重要性或价值），并由“so much”（极大地）修饰，用来表达深远的情感意义或价值。
Your support means so much to our team.
您的支持对我们团队来说意义重大。
EN： In English-speaking cultures, 'acts of kindness' (often referred to as 'random acts of kindness') are highly celebrated. There is a strong cultural emphasis on how small, everyday gestures—like holding the door or giving a compliment—can positively impact a community.
中文： 在英語系國家中，「善行」（通常被稱為「隨機善行」）非常受到推崇。文化上相當強調日常生活中微小的舉動（例如幫忙扶住門或給予讚美）如何能對社區產生積極正面的影響。
EN： The modal structure 'may have + past participle' is used to express a possibility or make a guess about a past event. It suggests that something was possible in the past, but the speaker is not 100% certain.
中文： 情态助动词结构“may have + 过去分词（p.p.）”用于表达对过去事件的可能性推测。这表示某事在过去是有可能的，但说话者并非百分之百确定。
She may have missed the bus this morning.
她今天早上可能错过了公交车。
EN： The word 'whole' is an adjective used before a singular noun to emphasize that the entirety of something is being referred to. It is often preceded by a possessive determiner (like 'my', 'his') or the definite article 'the'.
中文： 单词“whole”是一个形容词，置于单数名词前，用以强调指的是某事物的全部（整个）。它前面通常会加上所有格限定词（如“my”、“his”）或定冠词“the”。
He ate the whole cake by himself.
他自己一个人吃掉了整个蛋糕。
EN： In English-speaking cultures, leaving anonymous encouraging notes (like 'You can do it!') is a common, warm gesture of kindness in schools and workplaces to boost morale. The phrase 'changed my whole day' is a common idiom meaning a small positive event completely turned a bad or mediocre day into a great one.
中文： 在英語系國家的文化中，留下匿名的鼓勵紙條（例如「You can do it!」）是學校和職場中常見且溫馨的善意舉動，用以激勵士氣。片語「changed my whole day」是一個常見的慣用語，意指一個小小的正面事件，徹底將原本糟糕或平淡的一天變成了美好的一天。
EN： An indirect question is a question embedded inside another statement or question (e.g., 'who sent it' inside 'I still don't know...'). Unlike direct questions, indirect questions use statement word order (subject + verb) rather than question word order.
中文： 间接问句是嵌入在另一个陈述句或问句中的问句（例如在 'I still don't know...' 中的 'who sent it'）。与直接问句不同，间接问句使用陈述句的语序（主语 + 动词），而非疑问句语序。在此句中，who 同时作为疑问词与该从句的主语，后面直接接动词 sent。
Do you know where she lives?
你知道她住在哪里吗？
EN： The coordinating conjunction 'but' is used to connect two independent clauses that present contrasting ideas. In this sentence, it connects 'I still don't know who sent it' with 'I am grateful'.
中文： 并列连词“but”（但是）用于连接两个呈现对比概念的独立分句。在本句中，它将“我仍然不知道是谁寄的”与“我很感激”这两个完整的想法连接起来。
The test was difficult, but he passed it.
考试很难，但他通过了。
EN： The word 'whose' is an interrogative possessive determiner used to ask who owns something. It is followed directly by the noun it modifies (e.g., 'whose phone').
中文： 单词“whose”是疑问所有格限定词，用于询问某物归谁所有。它后面会直接接上所修饰的名词（例如：“whose phone”，意为“谁的手机”）。
Whose car is parked outside?
谁的车停在外面？
EN： The present continuous tense ('is ringing') is used to describe an action that is happening right now at the moment of speaking.
中文： 现在进行时（“is ringing”）用于描述在说话当下正在发生的动作。
The baby is sleeping in the room.
宝宝正在房间里睡觉。
EN： In English-speaking cultures, calling someone by their first name (like 'Emma') at the end of a question is a common way to get their attention directly and friendly, especially in casual settings.
中文： 在英語系國家中，在問句句尾直接稱呼對方的名字（如「艾瑪」）是日常生活中非常常見且親切的溝通方式，能直接吸引對方的注意。
EN： The modal verb 'might' is used to express weak possibility or uncertainty about a present or future situation. It is less certain than 'may' or 'must'.
中文： 情态助动词“might”用于表示对现在或未来状况的微弱可能性或不确定性。其确定性低于“may”或“must”。
It might rain later, so you should take an umbrella.
等一下可能会下雨，所以你该带把伞。
EN： The phrasal verb 'step out' means to leave a room or building for a short period of time, often used in casual or professional contexts.
中文： 短语动词“step out”意为暂时离开房间或建筑物，常用于日常口语或职场情境中。
Mr. Green just stepped out for a cup of coffee.
格林先生刚走出去买杯咖啡。
EN： In Western office and school culture, 'stepping out' is a very common, polite way to say someone has temporarily left their desk or room (e.g., to use the restroom, grab a drink, or take a quick call) but will return shortly.
中文： 在西方辦公室與學校文化中，「stepping out」是一個非常常見且禮貌的表達方式，用來表示某人暫時離開座位或房間（例如去洗手間、拿飲料或接個簡短電話），但很快就會回來。
EN： The modal verb 'can't' (cannot) is used to express a strong negative deduction or certainty about a present situation, meaning 'it is impossible that...'.
中文： 情态动词“can't”（不能、不可能）用于表示对目前状况的强烈否定推测或肯定，意思是“不可能……”。
That can't be the correct answer; it doesn't make sense.
那不可能是正确答案；这根本说不通。
EN： Possessive pronouns (such as 'mine', 'yours', 'his', 'hers', 'ours', 'theirs') are used to replace a possessive adjective + noun combination to avoid repetition. Here, 'mine' replaces 'my phone'.
中文： 所有格代词（如“mine”、“yours”、“his”、“hers”等）用于代替“所有格形容词 + 名词”的组合以避免重复。在此处，“mine”代替了“my phone”（我的手机）。
Your car is fast, but mine is more comfortable.
你的车很快，但我的（车）比较舒适。
EN： The modal verb 'must' is used here to express strong logical deduction or certainty based on evidence. It translates to '一定' (must be) in this context.
中文： 情态助动词“must”在此处用于表示基于证据的强烈逻辑推论或肯定。在这种语境下，它翻译为“一定（是）”。
She has been working all day, so she must be tired.
她工作了一整天，所以她一定累了。
EN： The coordinating conjunction 'so' is used to introduce a clause showing the result or consequence of the preceding statement.
中文： 并列连词“so”用于引导一个从句，以表示前述陈述的结果或影响（意为“所以”）。
It was raining, so we stayed indoors.
下雨了，所以我们待在室内。
EN： The modal verb 'could' is used to express possibility or uncertainty in the present or future. It suggests that something is possible, but not certain, similar to 'might' or 'may'.
中文： 情态助动词“could”在此处用于表示现在或未来的可能性或不确定性。它表示某事是有可能的，但并不完全确定，语气比“must”更委婉，类似于“might”或“may”。
The keys could be in your coat pocket.
钥匙可能在你的外套口袋里。
EN： The word 'outside' can function as an adverb or an adjective. In this sentence, it acts as an adjective modifying the noun 'wind', indicating the location of the wind relative to the speaker.
中文： 单词“outside”可以作为副词或形容词使用。在本句中，它作为后置形容词修饰名词“wind”（风），指出风相对于说话者的位置（外面的）。
The noise outside woke me up.
外面的噪音把我吵醒了。
EN： The modal verb 'must' is used here to express a strong logical deduction or certainty based on evidence. When combined with the base verb 'be' ('must be'), it indicates that the speaker is almost sure about a present state.
中文： 情态助动词“must”在此处用于表示基于证据的强烈逻辑推测或肯定。当与动词原形“be”结合（must be）时，表示说话者对目前的状态几乎可以肯定（译为“一定...”）。
He must be hungry after working all day.
工作了一整天，他现在一定很饿。
EN： The preposition 'after' is used to indicate that one event or state follows another in time. In this sentence, it connects the state of being tired to the preceding long trip.
中文： 介词“after”用于表示一个事件或状态在时间上接续在另一个之后。在本句中，它将“疲惫”的状态与先前的“长途旅行”联系起来（译为“在...之后”）。
We went for a walk after dinner.
我们晚餐后去散步了。
EN： The modal verb 'might' is used to express weak possibility (something that is possible but not certain). To make it negative, we add 'not' directly after 'might' ('might not'). Unlike verbs like 'do' or 'can', modal verbs do not change form for different subjects.
中文： 情态助动词“might”用于表示微弱的可能性（可能发生但并不确定）。若要形成否定句，直接在“might”后面加上“not”（might not）。与一般动词不同，情态助动词不会随着主语的人称而改变形式。
She might not come to the party tonight.
她今晚可能不会来参加派对。
EN： The adverb 'yet' is commonly used in negative sentences to indicate that something has not happened up to the present time, though it is expected to happen in the future. It is usually placed at the end of the sentence.
中文： 副词“yet”常用于否定句中，表示某事直到目前为止尚未发生，但预期未来会发生。它通常放在句子的末尾，中文常译为“还（没）”。
They have not finished their homework yet.
他们还没有完成他们的作业。
EN： The modal verb 'can't' (cannot) is used to express negative deduction or strong disbelief. When we are almost 100% sure that something is impossible based on evidence, we use 'can't be' followed by an adjective or noun.
中文： 情态助动词 'can't'（cannot）用于表示否定的推测或强烈的不相信。当我们根据证据几乎百分之百确定某事是不可能的时候，我们会使用 'can't be' 后接形容词或名词。
It can't be Ryan's jacket; his is much larger.
这不可能是莱恩的外套；他的外套大得多。
EN： The linking verb 'sound' is used to express an impression based on what has been heard or said. It is followed directly by an adjective (e.g., 'sounds impossible') to describe the subject.
中文： 系动词 'sound'（听起来）用于表达根据所听到的内容或说法所产生的印象。其后直接接形容词（例如 'sounds impossible'）来修饰主语。
That sounds great! Let's do it.
那听起来棒极了！我们做吧。
EN： The modal verb 'must' is used here to express strong deduction or logical necessity, meaning 'it is highly likely or certain that something is the case' based on available evidence.
中文： 情态动词“must”在此处用于表示强烈的推论或逻辑上的必然性，意思是根据现有证据“某事极有可能是真的”或“必定如此”。
He must be tired after the long trip.
长途旅行后他一定累了。
EN： The passive voice 'be hidden' (be + past participle) is used to focus on the receiver of the action (the answer) rather than the agent who hid it.
中文： 被动语态“be hidden”（be 动词 + 过去分词）用于将焦点放在动作的接受者（答案）上，而不是隐藏答案的人。
The key must be hidden under the doormat.
钥匙一定被藏在门垫下面。
EN： The structure 'Let's + base verb' (short for 'let us') is used to make suggestions or proposals, inviting others to do an action together.
中文： “Let's + 动词原形”（为 let us 的缩写）用于提出建议或提议，邀请他人一同参与某个行动。
Let's start the meeting now.
我们现在开始开会吧。
EN： The word 'before' acts as a conjunction here, introducing an adverbial clause of time ('before we guess') to indicate that the action in the main clause should happen first.
中文： “before”在此处作为连词，引导时间状语从句（before we guess），用以表示主句的动作应该先发生。
Wash your hands before you eat.
吃东西前要先洗手。
重要单词附有 IPA 发音、定义、例句和互动式测验。
在本文中： 属于，归……所有
在本文中： 发出嘎啦嘎啦的响声
在本文中： 线索，提示
在本文中： 想知道，纳闷
在本文中： 整洁的，工整的
在本文中： 非正式的，随意的
在本文中： 日程表，计划表
在本文中： 感激的，表示感谢的
片语包含类型标示、双语定义、用法说明和例句。
To be the property of someone.
属于……所有
To search for someone or something.
寻找
To leave a room or building for a short time.
暂时离开，出去一下