考点一 状语从句中的省略现象 (重点掌握,新课标常考)
1.当状语从句的主语和主句的主语一致时,可以省略状语从句的主语和系动词be,这时从句中可出现如下结构:
①连词(as,as if,once)+名词
Once(he was)a teacher,he now works in a government office.
他曾经是一位教师,现在在政府办公室工作。
②连词(though,whether,when)+形容词
Work hard when(you are)young,or you'll regret.
当你年轻时要努力工作,否则你会后悔的。
③连词(whether,as if,while)+介词短语
He looked everyone as if (he was)in search of something.
他打量每一个人似乎在寻找某个东西。
④连词(when,while,though)+现在分词
While(I was)walking along the street,I heard my name called.
我正在街上走,这时听到有人叫我的名字。
⑤连词(when,if,even if,unless,once,until,than,as)+过去分词
The exhibition is more interesting than(it was) expected.
展览会比预料得更有趣。
⑥连词(as if, as though)+不定式
注意:当从句的主语和主句的宾语一致时,间或也有这样的省略。
Her father told her to be careful when(she was) crossing the street.
她父亲告诉她过马路时要小心点。
2.当从句的主语是it,谓语动词中又含有系动词be时,可以把it和系动词be一起省略此时构成连词(if,unless,when,whenever)+形容词的结构。如:
Unless (it is) necessary,you'd better not refer to the dictionary.
除非有必要,否则你最好别查字典。
另外,我们还可以用so或not代替上文内容,此时可有it+so/not省略句式:
Get up early tomorrow. If not (you don't get up early),you will miss the first bus.
明天早起床。如果不能的话,你会错过第一辆公交车。
He may not be at home then,if so (he is not at home), leave him a note.
他可能不在家,如果这样,给他留下便条I