1.above / over / on / up

　　above：在……之上。指某物高过于另一物，与below相对。例如：

　　例782：The water came above our knees.(水深及膝之上。)

　　over：在……之上。指某物在另一物的正上方，互不接触，与under相对。例如：

　　例783：The lamp hangs over the table.

　　on：在……之上。指某物在另一物的上面，并相互接触。例如：

　　例784：The lamp stands on the table.

　　up：在……之上。指由低向高。例如：

　　例785：As they went up the mountain, they had to stop from time to time.

　　2.across / over / through

　　across：横过。指在同一平面上或成十字交叉穿过。例如：

　　例786：He was leading the blind man across the street. (他带着那个盲人过街。)

　　through：穿过。指从物体中间或空间穿过。例如：

　　例787：They walked through street after street, searching for a suitable dress.

　　(他们走街串巷，想找一件合适的礼服。)

　　over：越过。指跨过障碍物。例如：

　　例788：The thief climbed over the wall and ran away.

　　3.after / behind / at the back of

　　after：在……以后(表示时间);在……后面(表示地点，通常指次序的先后)。例如：

　　例789：Two days after his arrival, I called on him.

　　例790：They went out of the hall one after another.

　　例791：After you!请!(您先走!)

　　behind：在……后面。表示地点，指主体外部的后面，相对于in front of而言;它有时也表示时间，指针对某一规定时刻而迟了的意思。例如：

　　例792：There is a river behind our school.

　　例793：The train was behind time. (火车晚点了。)

　　at the back of：在……后部。表示地点，指主体内部的后部，相对于in the front of而言。例如：

　　例794：There is a playground at the back of our school.

　　4.after / in

　　after：在……以后(当其后接一段时间或过去某一时刻时，应使用过去时态;当其后接将来某一特定时刻时，应使用将来时态)。in：在……以后(后接一段时间，以现在为起点，表示将来)。例如：

　　例795：He will be back in two hours.

　　例796：He will be back after two o’clock.

　　例797：He was back after two hours.

　　例798：He was back two hours later / after.

　　5.among / between

　　among：在……之间。一般指在三个或三个以上的同类事物中。例如：

　　例799：The Yangtze is among the longest rivers in the world.

　　between：在……之间。一般指在两者之间或三者以上的每两者之间。例如：

　　例800：I dropped it somewhere between my house and the station.

　　例801：The tables in this restaurant are so close together that there is little room between them for people to move.

　　(这餐馆的桌子排得太密了，桌子与桌子之间几乎没有空间让人们移动。)

　　6.by turns / in turn / take turns

　　by turns的意思是“轮流地，交替地，忽而……忽而……”，强调重复。in turn的意思是“依次相继地”，强调按顺序，还有“转而，反过来”之意。表示“轮流地”时，take turns跟by turns同义，但二者的语法意义不同。例如：

　　例802：We had a swing by turns. (我们轮流荡秋千。)

　　例803：She went hot and cold by turns. (她一会儿发热，一会儿发冷。)

　　例804：The children got on the train in turn. (孩子们依次上了火车。)

　　例805：Interest rates were cut and, in turn, share prices rose.

　　(利率被调低了，而反过来，股票价格却上扬了。)

　　例806：Dan and I usually take turns to cook / in cooking.

　　7.except / but / besides / including / included

　　except：除……外，没有。指同类人、事、物的比较;另外，其搭配except for指不同类的人、事、物比较，except that，except when后接从句。例如：

　　例807：All the articles were well written except Ann’s. (同类物相比，即安的作文写得不好。)

　　例808：Ann’s article was well written except for some spelling mistakes.

　　(不同类物相比，即只不过有些拼写错。)

　　例809：Ann is a good student except that she is sometimes careless.

　　(跟从句，即只不过有时粗心。)

　　例810：The old lady often takes a walk except when it is raining. (跟从句，即下雨时不散步。)

　　but：除……外，没有。与except同义，但只用于who，all，no one，nobody，nothing，everyone或everything等代词后。例如：

　　例811：Who but Carl would do that?(除了卡尔，谁还愿意做那件事?)

　　例812：They had no choice but to give in. (他们只好屈服。)

　　例813：He does everything but cook. (他什么都行，就是不会做饭。此处的but前面有行为动词do，其后的动词应不带to。)

　　besides：作介词，意为“除……外，还有”;作副词，意为“况且，再说”。例如：

　　例814：All the students went besides their teachers.

　　例815：It’s getting dark; besides, it’s going to rain.

　　including / included：包括。注意它们不是介词，including是动词include的ing形式，included则是形容词。例如：

　　例816：All the students went, including Li Hua / Li Hua included.

　　(后者是独立主格，相当于and Li Hua was included。)

　　8.for the first time / the first time / the time

　　for the first time: 在句中作状语;the first time和the time在句中起着连词的作用。如：

　　例817：They were invited to the palace ball for the first time in their life.

　　例818：It was for the first time that he made such a mistake. (强调句型)

　　例819：It is the first time (that) he has made such a mistake.

　　例820：The first time I met him, he was feeding his sheep.

　　(此处语法意义上可以用the last time 或 the next time替换)

　　例821：The time the bell rang, all the pupils rushed out.

　　此处语法意义上可以用as soon as, the moment, the minute, the instant, instantly, immediately等替换;还可以用Hardly … when, Scarcely … when, No sooner ... than等倒装结构来表达。如：

　　例822：Hardly had the bell rang when all the pupils rushed out.

　　(铃声一响，所有的学生都冲了出去。)

　　9.in all / at all / after all / above all / for all / first of all

　　in all：总计(=in total)。at all：根本，全然(用于加强语气)。after all：毕竟。above all：首要(相当于the most important of all)。for all：尽管。first of all：首先。例如：

　　例823：First of all, I’d like to share the good news with you. For all the difficulties, we’ve managed to finish forty items in all. But we still have to work harder, and above all, we shall value every possible minute. After all, we have only ten days to go. We have no time to waste at all! (首先，我想和大家一起分享好消息：尽管存在种种困难，我们还是设法完成了总共四十个项目。然而，我们还得更加努力，最重要是要珍惜每分每秒，毕竟我们的期限只剩十天，我们的时间实在浪费不起啊!)

　　10.in the end / at the end of / by the end of

　　in the end：最后，终于。指时间，相当于at last或finally。例如：

　　例824：He waited and waited, but gave up in the end.

　　at the end of：在……末了，在……末端。指时间或地点。例如：

　　例825：At the end of the party, they added another program.

　　例826：You’ll find the post-office at the end of the street.

　　by the end of：在……结束时，到……末为止。常用完成时态。例如：

　　例827：We had learnt 24 units by the end of last term.

　　例828：We will have learnt 24 units by the end of this term.

　　11.in the past / in the past three years

　　in the past：过去(用过去时)。in the past three years：近三年(用现在完成时)。例如：

　　例829：Our town was poor in the past, but great changes have taken place in the town in the past / last three years. (我们的镇过去穷，可是近三年发生了翻天覆地的变化。)