2 ．across / over / through
across：横过。指在同一平面上或成十字交叉穿过。
例786：He was leading the blind man across the street 他带着那个盲人过街。
It's too wide. We can't swim across.这太宽了，我们游不过去。
When my name was called he looked across at me.当叫到我名字的时候，他从那边朝我看过来。从…的一边向目标
through：穿过。指从物体中间或空间穿过。
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。
The path led through the trees to the river.这条小路穿过树林通向河边。
The doctor pushed his way through the crowd.医生挤过人群。
over：越过。指跨过障碍物。
例788：The thief climbed over the wall and ran away .小偷爬过墙逃跑了。
They jumped over the stream.他们跳过了小溪。表示从某物的一边移至另一边只能用over：
Try not to knock that vase over.小心别把花瓶碰倒了。从直立位置向下和向外；落下；倒下
The wind must have blown it over.准是风把它吹倒了。
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789：Two days after his arrival I called on him .在他到达两天后，我去探望了他。
例790：They went out of the hall one after another .他们一个接一个走出大厅
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792：There is a river behind our school .我们学校后面有一条河
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794：There is a playground at the back of our school .我们学校后面有一个操场
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795：He will be back in two hours .他两小时后回来
例796：He will be back after two o’clock .他两点后回来
例797：He was back after two hours .两小时后他回来了。
例798：He was back two hours later 他两小时后回来了
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799：The Yangtze is among the longest rivers in the world .长江是世界上最长的河流之一。
between：在……之间。一般指在两者之间或三者以上的每两者之间。
例800：I dropped it somewhere between my house and the station .我把它掉在我家和车站之间的某个地方
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。 take turns轮流，交替
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 .Dan and I usually take turns in cooking .丹和我通常轮流做饭
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807：All the articles were well written except Ann’s .除了安的文章外，所有的文章都写得很好。 同类物相比，即文章与文章比。安的作文写得不好。
例808：Ann’s article was well written except for some spelling mistakes .安的文章写得很好，除了一些拼写错误
不同类物相比，即文章很好，有些拼写错误不好。只不过有些拼写错。
例809：Ann is a good student except that she is sometimes careless .安是个好学生，只是她有时粗心
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 .老太太经常散步，除非下雨。 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814：All the students went besides their teachers .除了老师，所有的学生都去了
例815：It’s getting dark; besides it’s going to rain .天快黑了，而且要下雨了
including / included：包括。注意它们不是介词，
例816：All the students went including Li Hua . Li Hua included .and Li Hua was included.所有的学生都去了，包括李华。
Li Hua included是独立主格，相当于and Li Hua was included。
I've got three days' holiday including New Year's Day.包括元旦在内我有三天假。
Food is included in the price. 饮食包含在该价格内。
I had worked hard to be included in a project like this .为参与这样的项目，我过去一直努力工作。