sit down . sit on a seat or resting place坐下

After the gym class Jim was tired and was glad to sit down and rest．体育课结束后，吉姆很累，因此很高兴能坐下来休息。

sit down . sit on the ground to express opposition静坐反对

All the students sat down and refused to leave the building．所有的学生都静坐，拒绝离开大楼。

sit down . suffer without protest or complaint逆来顺受

I couldn't sit down any longer．我再也无法忍受下去了。

sit for . take an examination应（考）；参加（考试）

His teachers said he should sit for university．他老师都说，他应该参加高考。

He sat for a scholarship and got one．他参加了争取奖学金的考试，并得到了奖学金。

sit for . be a member of parliament for a certain place代表…在议会占一个席位

He sits for a town in Cambridge shire．他是剑桥郡一个市镇选区选出的议员。

sit in . sit in a place，for a special purpose为某一特殊目的而坐在某处

He sits in with the patients while the nurse has a rest．护士休息的时候，他坐在那儿照看病人。

sit in . replace临时代替

The president is ill tonight so the secretary will be sitting in for her as chairman at the meeting．主席今晚生病，因此秘书将代她主持会议。

sit in .  demonstrate by sitting in a place坐某处示威

The students have been sitting in for the last two weeks．上两个星期学生一直在静坐示威。

sit in .  babysit替人临时照看婴孩

When her son and daughter-in-law went to the cinema，she had to sit in with their child．她儿子、儿媳去看电影时，她得替他们照看孩子。

 sit in on . attend as a visitor or an observer 作为来访客人参加

The professor said I could sit in on his linguistics lectures．教授说我可以旁听他的语言学课程。

Our teacher was invited to sit in on the conference．我们的老师应邀列席会议。

She sat in on the whole debate．整个辩论她都在场。

sit on . continue to sit继续坐着

She sat on until someone agreed to help．她一直坐到有人同意帮忙为止。

sit on . delay taking action on something 搁置；压下

They have been sitting on my job application for weeks．他们把我的求职申请压了好几个星期。

For weeks they did nothing about my case；they just sat on it ．他们好几个星期拒不审理我的案子，他们就是拖。

sit on . serve as a member of当…的一个成员

Mr． Brown sat on the jury at the trial．布朗先生担任陪审员。

He has been sitting on the English committee ever since he came to university．一进大学他就成了英语协会的一员。

sit on .  quickly subdue somebody who behaves rudely or impertinently申斥；压制

Her brother sat on her firmly whenever she was too noisy or silly．每当她太吵或太蠢时，她哥哥都要训斥她。

The teacher sat on Jack as soon as he began showing off．杰克一开始卖弄小聪明，老师就马上加以制止。

sit out . remain seated during a dance坐着不跳舞

I think I'll sit out the next dance；I'm tired．下一个舞我不想跳了，我很累。

sit out .  stay until the end of（a play）看完（戏）

I decided to sit out the rest of the film although I was not especially enjoying it， but my friends were．虽然我并不太喜欢这部电影，可是我的朋友们喜欢，因此我决定还是把它看完。

It was a tedious show and very few people sat it out．那部电影冗长乏味，很少有人坚持看完的。

sit out . stay longer than比…留得久

It was her turn to leave， but she decided to sit the other women out．该她走了，可她却决定等其他妇女都走后再离开。

I wonder which of the visitors will sit out the other．我不知道两位客人中哪一位坐得更久。

sit out . sit out of doors坐在室外

Isn't it nice when the sun is warm enough for us to sit out? 太阳暖洋洋，我们坐到室外去不是很好吗?

sit through . watch or listen until something  is finished看完或听完

Though he was busy，he sat through the performance of the play．尽管忙，他还是坚持看完这剧的演出。

We had to sit through the first half of the film without the sound．电影的前半部分我们是在无声中看完的。

sit tight . make no move or change坐着不动

Mother told her little son to sit tight until she came back．母亲告诉孩子坐着不要动，等她回来。

Sit tight；I'll be ready to go in a few minutes．等等，我一会儿就走。

sit tight . stick to one's opinion坚持意见

I was unable to dissuade him． He is still sitting tight with regard to his opinion that he ought to leave his present job．我无法劝阻他，他仍然固执己见，要辞去他现在的工作。

Both of them sat tight with their own arguments．他俩各执己见，互不相让。

sit up . move into a sitting position坐起身来

Joe sat up when he heard the knock on his bedroom door．乔听到有人敲寝室的门，就坐起身来。

She sat the old man up in bed．她扶老人起来坐在床上。

sit up . stay awake instead of going to bed迟睡；熬夜

Mrs．Jones will sit up until both of her daughters get home from the dance．琼斯夫人要等到她两个女儿跳舞回来后再休息。

I'll be late tonight． Don't sit up for me．今晚我回来得迟，不要等我。

sit up .  be surprised惊讶

Janice really sat up when I told her the gossip about Tom．当我把有关汤姆的流言蜚语告诉詹妮丝时，她确实很惊讶。

You should have seen them all sit up as soon as I mentioned money．你应该注意到，当我一提起钱的时候，他们个个都警觉了起来。