俞江涛

请看下题：

He was educated at the local high school, ____ he went on to Beijing University.

A. after which B. after that C. in which D. in that

本题把介词和定语从句的用法综合到一起。从句式看，可以先排除B和D。因为B项中的after是一个介词，不能连接两个句子，可以改为He was educated at the local high school, and after that he went on to Beijing University。B项如果引导的是定语从句，介词后面不能加that，表示事物可以加上which，而D项in that作连词用意思是“因为”，很明显“他继续上北京大学”不是“他在当地中学读书”的原因。正确答案为A项，很多同学会误选C。

错误的原因在于混淆了介词表示时间还是表示地点。从语境看，本句表达的意思是“他在当地的中学读书，之后他继续上了北京大学。”因此此处的介词表示了时间的先后关系。如果使用in which则表示“他在当地的中学读书，期间他继续上了北京大学”或理解为“他在当地的中学读书，在当地中学他继续上了北京大学”，很显然不符合语义逻辑。再如：

There were a lot of people standing at the door and the small girl couldnt get ____.

A. between B. through C. across D. beyond

本题考查了介词表示空间的用法。四个选项都可以表示地点。between强调在两者之间；through表示从内部通过、穿过；across强调横穿；beyond在……的那一边。题干表达的意思是“门口站着很多人，小女孩进不去（从门口进入）”。所以使用get through。

介词既可以表示时间、也可以表示空间，这是介词最基础、最常见的用法，掌握该用法的关键要从以下几个方面来辨析介词的“时”、“空”用法，才能和介词手牵手，自由、潇洒地穿越于“时”、“空”之中。

一、表示时间

1. 时间的大小各不同

【例句】

①As a middle school student in a small city, I have to get up at 6 every morning.

②The 2008 Chinese Spring Festival falls on February 7.

③The 2008 Beijing Olympic Games will be held in August.

[辨析] at表示时间的一点，时刻，如：at 12∶00,也可以表示“在黎明、中午、夜间”。如：at dawn/at daybreak 在黎明时候；at noon 在中午；at night 在夜里；at midnight在半夜。on表示具体的日子或特定的时间，如某日、星期几、某个特定节日。如：on August 8, on a cold morning, on Monday, on National Day。 in则表示较长的时间，如世纪、朝代、年、季节、月份，也可以泛指上下午、晚上等。如： in the 1990s, in the Ming Dynasty, in May, in the morning。

2. 时间的点和段要分清

【例句】

①The 2008 Beijing Olympic Games will be held in four months.

②I will go abroad to study for my master degree after July.

③I have learned English for 6 years.

④I have learned English since 6 years ago.

[辨析]in和after都可以表示“在……之后”用在一般将来时中，in 后面加表示一段时间的状语（“四个月”是一段时间）;after后面的时间表示时间点（“七月份”是时间点）；for后面加段时间（“六年”是一段时间），since后面接的时间表示时间点（“六年前”是时间点）。

3. 从泛指和特指方面来攻关。

【例句】

①We usually have PE classes in the afternoon.

②The opening ceremony of the 2008 Beijing Olympic Games will be held on the morning of 8, August.

③I have a practice of surfing the Internet at night, but I had to finish my homework on the night of last Monday.

[辨析] 表示泛指的“在上下午、晚上”用in，但特指在某天的上下午、晚上则使用on；表示泛指的“在黎明、中午、夜间”使用at，但是特指某天的黎明、中午、夜间则用on。

4. 时间的先后不含糊

【例句】

①His father died in Wuhan at last March.

②His father had gone abroad to do business by last March.

③His father has been doing business abroad since last March.

[辨析] at表示就在某个时间点，by表示在某个时间之前，since表示从某个时间之后。在区别这几个介词时要注意根据句子的时态来判断时间的先后。

二、表示空间

1. 区别空间的方位

【例句】

①The horse jumped over the fence and ran across the field. Beyond the field flowed a river.

②Taiwan lies in the east of China; Japan lies to the east of China; Korea lies on the east of China.

③The university is opposite a factory, between a hospital and a post office.

[辨析]over表示从上方越过，across表示横越，beyond表示在……的那一边。in强调在……内的某个方向，to强调两个地点不相连，on强调两地接壤。opposite表示在……对面。between表示在（两者）之间。

2. 区别所在空间的动态和静态。

【例句】

①When I came into the room, he was in the sofa.

②Mr. Smith was walking along the coast when he found a beautiful cottage on the coast.

[辨析] into是动态介词，强调由一处进入另一处，in是静态介词，表示处于某个位置。along常用作动态介词，和动词连用表示“沿着……”，on是静态介词，表示与线或面接触的地方。

3. 区别空间的大小

【例句】

①He lives at 88 Xianggang Road.

②He lives in Wuhan.

[辨析] at表示小地点，in表示大地点。

介词的用法林林总总，除了表示时空的基本用法以外，还可以表示目的、方向、原因、程度等。需要同学们注意的是大部分介词经常和动词、名词、形容词构成固定短语，因此我们在平时的学习中要逐步积累、不断体会。

【巩固练习】

1. ——Where is the post office?

——You can find it ____ 2336 Fire Road.

A. on B. in C. near D. at

2. We can see a lot of people doing exercises in the parks even ____ a cold morning.

A. at B. in C. by D. on

3. Your mother will be back ____ a few minutes, but your father will be back ____ ten oclock.

A. after; after B. in; in C. in; after D. after; in

4. Hubei lies ____ the north of Hunan, which is ____ the middle of China.

A. to; on B. on; in C. in; in D. on; on

5. The train leaves ____ 6:00 p.m. So I have to be at the station ____

5:40 p.m. at the latest.

A. at; until B. for; after

C. at; by D. before; around

6. The enemy got beaten and fled ____ all directions.

A. to B. toward C. for D. in

7. Can you see the heavy smoke ____ the skyscraper? What is

happening over there?

A. through B. beyond C. on D. across

8. The doctor will be free ____.

A. 10 minutes later B. after 10 minutes

C. in 10 minutes D. 10 minutes after

9. The sunlight came in ____ the windows in the roof and lit up the whole room.

A. through B. across C. on D. over

10. He suddenly saw Jane ____ the room. He pushed his way ____ the crowd of people to get to her.

A. across; across B. over; through

C. over; into D. across; through

Key(3)