at /ˈæt/ /ət/ preposition Learner's definition of AT
1
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used to indicate the place where someone or something is在…里；在（某处） -
We're staying at a hotel.我们待在宾馆里。
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The kitchen is at the back of the house.厨房在房子后面。
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He was sitting at the table.他坐在桌旁。
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They left for Cambridge early and arrived at [=in] Cambridge before noon.他们一早出发前往剑桥，在中午之前到达。
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The party will be at Susan's house. = The party will be at Susan's.聚会将在苏珊家举行。
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Ann works at [=in] a library.安在图书馆工作。
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We met at a party.我们在一次聚会上相遇。
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They live at opposite ends of town.他们居住在镇子相对的两头。
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They met at [=on] a street corner in a town.他们在一个小镇的街角碰面。
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“Is your father at home?” [=is your father home?] “No, he's working late at the office.”“你父亲在家吗？”“他不在家，他在办公室加班。”
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She met us at the door.她在门口接我们。
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He was standing at [=next to] the window.他正站在窗边。
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There were 200 people at the wedding. [=200 people attended the wedding]有200人参加了婚礼。
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Their older son has graduated, but their younger son is still at school. [=is still attending school]他们的大儿子毕业了，但小儿子还在上学。
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Who was at the controls when the accident occurred?事故发生时，谁在开车？
2
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used to indicate the person or thing toward which an action, motion, or feeling is directed or aimed向；朝；以…为目标 -
She pointed her gun at the target.她用枪瞄准了目标。
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He's angry at his brother.他很生哥哥的气。
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His anger is directed at his brother.他把气都撒在哥哥身上。
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She shouted (words of) abuse at me.她大声辱骂我。
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He looked directly at me.他直视着我。
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They laughed at him.他们嘲笑他。
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She grabbed at my arm. [=she tried to grab my arm]她想要抓住我的胳膊。
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He poked at his food.他拨弄着他的食物。
3
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used to indicate something that is being tried or attempted从事；忙于 4
: because of or in reaction to (something)因为；由于；对…回应 —
used to indicate the cause of an action, feeling, etc.用于指引起某种举动、情感等的原因 -
I was greatly surprised at [=by] the result. [=the result surprised me greatly]这个结果让我大吃一惊。
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He enlisted in the army at his father's urging. [=because his father urged him to]由于父亲的主张，他加入了陆军。
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She visited the museum at my suggestion.她听从我的建议参观了那家博物馆。
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They came here at our invitation.他们应我们的邀请来到这里。
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You can act at your own discretion.你可以自主行事。
5
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used to indicate an activity处于…活动 -
He's very serious when he's at work. [=when he's working]他工作时很严肃。
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children who are at play [=children who are playing]正在玩耍的孩子们
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She's good at (playing) chess. [=she plays chess well]她擅长下国际象棋。
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I'm bad at cooking. [=I'm a bad cook, I do not cook well]我不擅长烹饪。
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She's doing very well at her studies.她学习非常棒。
6
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used to indicate a situation or condition处于…状态 -
I'm not at liberty to discuss that.我现在无权讨论那个问题。
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at rest处于静止状态
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two nations that are at war处于战争状态的两个国家
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people who are at risk处于险境的人
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He is now at peace.他现在平静了。
7
a —
used to indicate position on a scale or in a series达（表数值） b —
used to indicate a rate以（表价格） 8
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used to indicate an age or time在…岁时；在…时间 -
He plans to retire at (age) 65.他计划65岁退休。
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He called us at (about/exactly) 9 o'clock on July 24.他7月24日（大约/整）9点给我们打的电话。
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at dawn/noon/sunset/night在凌晨/中午/傍晚/夜晚
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I still think of her at certain moments/times.我现在在某些时刻还是会想起她。
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He was president of the company at (the time of) his death.他去世时任公司总裁。
9
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used to indicate the method by which something is done通过；经由 10
a —
used in phrases like at best, at worst, etc., to indicate a possible result or condition that is considered best, worst, etc.最好的，最糟的（用于at best、at worst等短语） -
The company will make a small profit at best this year. [=it is not possible that the company will earn anything better/more than a small profit]公司今年顶多是微赢利。
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We might be 5 or 10 minutes late at worst. [=we will not be more than 5 or 10 minutes late]我们可能最多也就是迟到5或10分钟。
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We should arrive by noon at the latest. [=we should not arrive later than noon]我们最迟应该在中午到。
b —
used in phrases like at its best, at its worst, etc., to indicate that something or someone is as good, bad, etc., as possible处于最佳（或最差）的状态（用于at its best、at its worst等短语） -
This is baseball at its best.这是最精彩的棒球比赛。
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He's often rude, and last night he was at his worst.他经常很无礼，昨晚无礼到了极致。
◊ The word at is used in speech in e-mail addresses.单词at用于口述电子邮件地址时。
In writing, the symbol @ is used instead.在书面语中，用符号@代替。
at it
: doing some activity做某事 -
I didn't expect her to have started working yet, but she was already (hard) at it when I arrived. [=she was already working (hard) when I arrived]我本来没指望她开始工作，但我到的时候她已经在（努力）干活了。
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My neighbors are always arguing, and they were at it again last night. [=they were arguing again last night]我的邻居总是吵架，昨晚他们又吵起来了。
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Since we're cleaning the kitchen, we should wash the floor while we're at it. [=we should wash the floor when we clean the kitchen]既然要打扫厨房，我们应该同时把地板也擦了。
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“I'm going to the store to buy a newspaper.” “While you're at it, could you get some milk?”“我要去商店买份报纸。”“你买报纸时，顺便买点牛奶好吗？”
where (someone) is at
— see 1where