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sat down
这里是动词用法：sat 是 sit 的过去式和过去分词；sat down 表示“坐下”。
She sat down and took a deep breath.
她坐下来，深吸了一口气。
坐；就座
sats — third person singular of sat
先理解核心含义，再看它在真实句子里的用法。
坐；就座
past tense and past participle of sit
She sat down and took a deep breath.
她坐下来，深吸了一口气。
We sat on the bench and watched the sunset.
我们坐在长椅上看着日落。
She sat down at the table and began to eat.
她在桌边坐下来，开始吃饭。
The patient sat still while the doctor examined him.
医生检查时，病人静静地坐着。
这里是动词用法：sat 是 sit 的过去式和过去分词；sat down 表示“坐下”。
She sat down and took a deep breath.
她坐下来，深吸了一口气。
sat 后接地点状语，表示“坐在某处”。
He sat by the window, reading a book.
他坐在窗边看书。
sat around 表示“无所事事地坐着”，后接 -ing 形式表示伴随动作。
We sat around talking until midnight.
我们闲坐着聊天，一直到午夜。
sat for 表示“坐着供人画像或拍照”。
She sat for a portrait by a famous painter.
她坐着让一位著名画家为她画像。
Not this
He sitted on the chair.
Use this
He sat on the chair.
「sit」是不规则动词，过去式是「sat」，不能直接在原形后加-ed 构成「sitted」。改为「sat」才是正确的一般过去时形式。
Not this
Yesterday she sit next to me.
Use this
Yesterday she sat next to me.
时间状语「yesterday」表明句子需要用一般过去时，而「sit」是原形。应使用「sit」的过去式「sat」来表示过去的动作。
Not this
They sat in this café since morning.
Use this
They have sat in this café since morning.
「since morning」表示从过去延续到现在的状态，应当使用现在完成时「have sat」，而不能用一般过去时「sat」。
Focus on the distinctions below. Other candidates are kept compact until a reliable usage note is available.
坐下
He sat down on the sofa.
他在沙发上坐了下来。
坐起来；坐直
She sat up in bed when the phone rang.
电话铃响时，她在床上坐了起来。
向后靠坐；放松地坐着
He sat back and enjoyed the view.
他向后一靠，欣赏着风景。
闲坐，无所事事
We sat around and chatted all afternoon.
我们闲坐了一下午，聊着天。
耐着性子听完/看完
I sat through the whole lecture without falling asleep.
我耐着性子听完了整场讲座，没有睡着。
担任委员会成员
She sat on the finance committee for five years.
她担任了五年财务委员会委员。
持观望态度；犹豫不决
He sat on the fence during the debate and refused to pick a side.
他在辩论中持观望态度，拒绝选边站。
耐心等待；按兵不动
We sat tight until the storm passed.
我们耐心等待，直到暴风雨过去。
处境有利；过得舒服
After the deal, she sat pretty with a steady income.
交易达成后，她收入稳定，处境很好。
我坐在岸边垂钓，身后是干旱的平原。（出自T.S.艾略特长诗《荒原》）
He sat on the porch and watched the rain.
他坐在门廊上看着雨。
我坐在地毯上，静待时机，喝着她的酒。（出自披头士乐队歌曲《Norwegian Wood》）
They sat around the fire and told stories.
他们围坐在火旁讲故事。
Use sats naturally, then get feedback on meaning, tone, grammar, and phrasing.
Revisit a common error or keep this word in your review list.
联想：sit 的 i 变成 a 就是 sat，a 像小板凳，人已坐下来。
语域：neutral 常见场景：日常对话、书面表达 sat 是 sit 的过去式和过去分词，通常用于中性语域，日常对话和书面表达中都比较常见；在 sit around（闲坐）等短语中偏口语，在 the court sat（开庭）等搭配中偏正式，具体需结合语境判断。
These words rhyme with sat: cat, rat, mat, hat, bat, fat all have the vowel /æ/ followed by /t/. Be careful with lookalikes that sound different: set /sɛt/, sate /seɪt/, and seat /siːt/; do not infer the sound from the spelling.
Dictionary facts from ECDICT, WIKTIONARY.