(1)让，允许(allow to do sth;permit)[C+n+to-inf，无pass](如上下文清楚，常略去后面的不定式)：He won't～us do it . 他不准我们做此事。We can't～this go on. 我们不能让这事继续下去。Will you～me smoke? 我能抽烟吗? I'd love to come but my parents won't～me. 我很想去，但是我的父母不让。〖反〗forbid，prohibit;
 (2)准许活动、进入或通过(allow to move，enter or pass)[T+n+prep，T+n+adv]：Who～you into the building? 谁让你进入这座大楼的? Please～me in/into the room. 请让我进来。～the dog out (of the room) 把狗(从屋子里)放出去;～sb by/past 让某人过去;～the curtain down 放下窗帘;～in light and air 让光线和空气进来;～sb through/a report through 让某人通过/通过一报告;
 (3)(用于祈使句)(used as an imperative)[C+n+to-inf，无pass]1)让，允许(allow) (let us不可缩写为let's)：L～us know what you're going to do. 请告诉我们你们要做什么。L～us buy you a drink. 我们来请你喝一杯。L～me try. 让我来试一试。2)(用于提出建议或计划，包括对方在内，let us常缩写为let's)：“L～'s go for a walk. What do you say?”“All right. L～'s.”“咱们去散步吧。你意下如何?”“好吧，咱们去吧。”L～'s go for a ride/go home. 咱们去兜风吧/回家去吧。Mama，you're ill. L～me get the doctor. 妈妈，你病了。我去请医生吧。L～'s not get angry/Don't ～'s get angry. 我们不要发火。(注意上述否定句，前一句被认为更加正确，在书面语中比第二句更常见。) 3)(表示要求、命令或威胁等)： L～him be here by ten o'clock/him tell all the facts. 叫他10点以前到这儿来/把实话都说出来。L～every man do his duty.人人都要尽责。If they will not work，～them starve. 他们不愿意干活就让他们挨饿。4)(表示假设)： L～AB be equal to CD. 设AB等于CD。 L～X be the unknown quantity. 设X为未知数。
 (4)出租(allow to use in exchange for regular payments)[T+n，T+n+prep(to)，T+n+adv(out/off)，I]：～(out)a house/cottage/shop/flat/room/field (to sb) 把房子/小型别墅/商店/公寓/房间/一块田地出租(给某人);have rooms to～有房屋出租;～a boat by the hour/at low rents 以小时计费/低租金租船;～the top floor of one's house to two young men 把房子的顶层租给两个年轻人;The six floors of this large building were～off as separate flats. 这座大楼中有六层是按套房出租的。This house is to (be)～. 此房出租。To～. 出租(招牌用语)。The apartment～s on a yearly basis. 这套公寓按年出租。〖同〗rent;
 let sb/sth be 不要打扰 L～her be;she has a headache. 不要打扰她，她头疼。
 let bygones be bygones 过去的事情就算了，既往不咎：We should～bygones be bygones and try to get along with each other. 我们应该既往不咎，和好相处。
 let drop/fall(似乎无意，实则有意)说出，故意漏出：He～drop the suggestion that we should meet him in town. 他似乎无意地提出我们应该在城里同他会面。
 let go (of)放开，松手：He～go the boy. 他松开抓着男孩的手。Don't～go of the dog. 不要放开这只狗。
 let it go(at that)算了，就此为止：I don't agree with all you say but we'll～it go at that. 你说的话我不是都同意，但是我们就此为止吧。
 let oneself go 1)言行随便，不拘束：Judge Brown～himself go at the reunion of his old class and had a good time. 布朗法官在老同学的聚会上很随便，玩得很痛快。2)放松，松懈：The cowboys worked hard all week，but on Saturday night they went to town and～themselves go. 牛仔们整个星期辛苦地工作，但是星期六晚上他们去城里尽情地玩个痛快。
 let loose 放开，让自由活动：He caught her arm and would not～loose. 他抓住她的胳膊不放手。～a dog loose 放开狗让它自由活动;
 let me see 让我想一想：L～me see. Where did I put the key? 让我想一想，我把钥匙放哪儿了?
 let sleeping dogs lie (prov)莫惹是非：Don't tell Father that you broke the window. L～sleeping dogs lie. 不要告诉爸爸你打破了窗户玻璃，别惹麻烦。
 let the cat out of the bag泄露秘密，露馅：We wanted to surprise Mary with a birthday gift，but Allen～the cat out of the bag by asking her what she would like. 我们想意外地送给玛丽一件生日礼物，但是艾伦问她想要什么就露了馅。
 let well enough alone 满足于已经很好的事，不要过头：John wanted to make his kite go higher，but his father told him to～well enough alone because it was too windy. 约翰想让风筝飞得再高一点，但是他父亲告诉他因为风太大，这样已经够高了。
 let down (v adv) 1)辜负，使失望，失信(vt)：The team felt they had～the coach down. 队员们感到辜负了教练的期望。I've been badly～down. 我非常失望。2)放长(衣服)(vt)：～a hem down 放出折边;She～the dress down several centimeters. 她把那件女衫放长了几厘米。
 let in (v adv) 1)渗，漏(vt)：These shoes～in water. 这些鞋子漏水。2)把衣服改瘦些(vt)：The trousers need～ting in at the waist. 这条裤子的腰部需要改瘦些。
 let in for (v adv prep) 使陷入麻烦等(vt)：It could～us in for trouble. 这可能会使我们陷入麻烦。
 let in on/into (v adv prep/prep) 使知道(秘密等)(vt)：I've heard something very funny and I'll～you in on it after class. 我听到一件很有趣的事，下课后告诉你。She has been～into the secret. 她已得知了那个秘密。
 let off (v adv) 1)开枪，引爆，燃放(vt)：～off guns/fireworks/a bomb 开枪(炮)/燃放烟火/引爆炸弹; 2)放过，饶恕(vt)：She～him off lightly. 她轻易放过了他。～sb off with a fine/without punishment 对某人罚款了事/免于惩罚; 3)放出(vt)：～off steam 放出蒸汽; 4)允许不做某事，放假(vt)：The teacher～the students off their homework that evening. 老师那天晚上没给学生留作业。He was～off for a week's vacation. 批准他度假一周。
 let on (v adv) 1)泄露，让人知道(vt & vi)：Don't～on that I was late. 别告诉别人我迟到了。I never～on about what you told me. 你对我说的话我从来都没讲出去。He knew where the boy was but he didn't～on. 他知道那个男孩在哪儿，但他就是不说。2)假装(vt & vi)：The old man likes to～on that he is rich. 那个老人喜欢装出他很富有。He～on like he didn't hear a word they said. 他假装好像没听见他们说的话。
 let out (v adv) 1)让出去(vt)：Mother won't～us out when it rains. 下雨时妈妈不让我们出去。2)发出(vt)：～out a sigh/shriek 叹一口气/发出一声尖叫; 3)泄露，说出(vt)：～out a secret/the news 泄露秘密/透露消息; 4)放宽(长)衣服(vt)：His trousers need to be～out round the waist. 他的裤腰需要放宽。5)加速(vt)：He turned into an expressway and～the car out. 他把车子开上高速公路，然后加速前进。6)免除责任(义务等)(vt)：Frank has shoveled the snow from the sidewalk. That～s me out.弗兰克已经把便道上的雪铲走了，我就不用干了。7)解雇(vt)：Some workers will probably be～out. 有些工人可能要被解雇。8)结束(散)(vt & vi)：The coach～us out from practice at three o'clock. 教练3点钟结束训练让我们解散。School～s out at four o'clock. 学校4点钟放学。
 let slip 1)无意说出：The girl～slip that she had been a witness to the accident. 那个女孩无意中说出她是那次事故的目击者。2)错过：We mustn't～slip such an opportunity. 我们一定不要错过这样一个机会。
 let up (v adv) 1)减小(弱)(vi)：The rain/snow～up. 雨/雪渐渐小了。2)松劲，停止(vi)：They didn't～up，even though they were winning. 即使快赢了他们也不松劲。He works all day and never～s up. 他整天工作，一刻也不休息。
 →′let-down n 失望;′let-up n 减少，放松，和缓;
 【辨异】1)let与allow和permit的区别见ALLOW。2)let与hire和rent的区别见HIRE。