3. 状语从句中的省略

【点拨】含有when, while ,until, if, unless, once, before等引导的状语从句的主从复合句中，若从句的主语和主句的主语一致，并且从句中谓语动词有be的某种形式，从句中的主语及部分谓语(be动词)可以省略。例如：Be careful when crossing the street. Some students like studying while listening to the tape.

【点击高考】When________ , the museum will be open to the public next year.(2002上海)

A. completed B. completing C. being completed D. to be completed

【解析】答案是A。这是一个省略句，从句省略了the museum is。原句是：When the museum is completed, the museum will…。

【巩固练习】用括号里所给的动词的适当形式填空：

(1) When __________ (work) with the workers, we learned a lot from them.

(2) When ___________ (ask) , he always gives good advice.

(3) He will not go the party unless __________.(invite)

(4) The research can not be stopped once____________. (begin)

答案：(1)working (2)asked (3) invited (4) began

4. 代/名+介词+which引导的定语从句

【点拨】这样的定语从句一般是非限制性定语从句，which在从句中作介词的宾语，代指前面的物或事。例如：They all come from the USA, most of whom are scientists.他们都来自美国，大部分是科学家。We had a meeting, the purpose of which was completely unclear. 我们开了一个会，会议的内容还不完全清楚。

【点击高考】Recently I bought an ancient Chinese vase, __________ was very reasonable.(2002上海)

A. which price B. the price of which C. its price D. the price of whose

【解析】答案是B。这是一个非限制性定语从句，the price of which指代花瓶的价格，等于whose price。

【巩固练习】(1)There are two buildings, ________ stands nearly a hundred feet high.(2004 湖北)

A. the larger B. the larger of them C. the larger are that D. the larger of which

(2)The factory produces half a million pairs of shoes every year, 80%_______ are sold abroad.(2004辽宁)

A. of which B. which of C. of them D. of that

答案：(1) D (2) A

5. –ing作状语

【点拨】动词的-ing形式作状语时，应该注意以下三个方面：(1)分词表示的是句子主语发出的动作;(2)分词表示的动作和谓语表示的动作或状态是同时发生或先后发生;(3)分词表示的是次要的动作，一般是对谓语表示的动作或状态加以说明。常用来表示伴随、原因、时间和结果等。例如：He often sits on the sofa, watching TV. (伴随)The bell which indicated the end of the class rang, interrupting our heated discussion. (结果)

【巩固练习】用括号里所给动词的适当形式填空

(1) _________ so poor in those days, they couldn’t afford to send their son to school.(be)

(2) _______ out of the room, he found the boy still there.(walk)

(3) His wife died in 1990, _________ him two children.(leave)

(4) They stood there for an hour, __________ the game.(watch)

答案：(1) Being (2) Walking (3) leaving (4) watching

词语辨析

1. sometimes, sometime, some time 和some times 四个词的区别。

sometime 是副词，意思是：在某时。表示不确定的时间，可以与将来时也可以与过去时连用;sometimes是频度副词，意思是：偶尔，有时。常与一般现在时或一般过去时连用;

some time是名词词组，意思是：一段时间。常指将来;some times是名词词组，意思是：几次，几倍。

【例句】I usually go to school on foot, but sometimes I go to school by bike.

I saw him sometime last winter.

She will stay in Beijing for some time.

I met him some times in the street last week.

2. if only与only if的区别

if only的意思是：但愿，要是……就好了。常引导虚拟语气。only if的意思是：只要……。引导陈述语气的真实条件句。

【例句】Only if you study word, you will pass the exam.

If only I had not been late yesterday.

3. be about to do, be to do 与be going to

be about to do 表示即将发生的动作，不表示按计划安排的活动，不与表示将来的时间状语连用。be going to 表示“打算/计划做某事”，它表示按计划安排要发生的事或者有迹象表明某事要发生。be to do 表示“按计划或打算要做的事”或者表示“要求、命令、禁止、注定等”。它所表示的动作是事先安排好的受到人的主观意识的控制。

【例句】He was about to leave when the telephone rang.

It is going to rain.

You are to do your homework in ink.

4. like与as做介词时的区别

like与as它们两个都可以做介词用。但like的意思是：像;类似;后接名词、代词或动名词。而as的意思是：作为，当作，当某人是(某身份)时。

【例句】I’ve always wanted a garden like yours.

As a child, he lived in India.

5. take, spend, cost与pay的区别

spend 的主语必须是“人”，宾语可以是“钱、精力、时间等”，其后用on+名词或者in + doing，in可以省略。cost 的主语必须是“物”或“事”，表示“费用，耗费”，后接life , money, health, time , money等，侧重于“花费”的代价。 take 表示“花费”时，其主语一般是“一件事”，通常用it做形式主语。pay 的意思是“支付”，宾语可以是“人、钱”等，常和介词for搭配。

【例句】The money he spent on the books added up to 500 yuan.

It took me five hours to finish the work.

The money I paid for the clothes was 800 yuan.

How much did it cost ?