2012年12月大学英语四级语法：比较状语从句

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2012年12月大学英语四级语法：比较状语从句
比较状语从句：
　　than, as…as…，not so as…，（not) the same as, the+比较级；
　　eg：Light travels fast than sound.
, n$ J- R, _2 M0 P" R9 t% L　　the+比较级：
7 l- O3 `1 l- p　　eg：The sooner，the better.
3 A$ q8 ~( [2 Q6 n% o8 u! b0 r6 Y　　eg：Girls are thus seen as less valuable than boys and art kept at home to do housework while their brothers are sent to school - the prophecy（预言) becomes self- fulfilling, trapping women in a vicious circle (恶性循环) of neglect.
　　（1）当……的时候：while, when, as ；
5 \; Y4 ]8 K' f5 `7 d　　when：强调一件事情正在发生的时候，另外一件事情突然发生；
# ~* n) f, U( u& |3 n7 K　　eg：When I was watching TV, my mother came back.
7 c, @2 [7 \/ q- {　　while：强调两个动作同时进行，一边……一边……；
　　eg：My father is cooking while my mother is reading newspaper. 中华考试网
　　as："随时间推移"
+ E( ]* m" i' c7 v. m5 U: I　　eg：As time went by, the days became longer and longer.
　　（2）一……就……：as soon as ,主将从现；用directly，immediately, instantly连接两个句子；一些名词如the minute，the moment, the instant也可表示；no sooner… than, hardly… when后面的句子需要倒装；
　　eg：I will write to you the moment/minute I arrived in Paris.
　　（3）特殊单词：by the time that, every/each time（使用时后面不要再加when）
　　（4）till＆until：
& G" y% M% Q1 L　　① 肯定形式表示的意思是"做某事直至某时"，动词必须是延续性的；
: L$ Y, x7 c* ?3 q" H. W　　否定形式表达的意思是"直至某时才做某事"，一般用until，动词为延续性或非延续性都可以；
  W) x& q; d1 a3 x　　eg: I slept until midnight.
) O3 Q+ J1 q2 B# j6 ~/ v: H9 c; N　　Wait till I call you.
, C7 S9 n9 Z( {  `1 r0 }　　She didn’t arrive until 6 o’clock.
　　② Until可用于句首，而till通常不用于句首，通常用于句中；
　　eg: Until you told me, I had heard nothing of what happened.
　　eg：As you sleep you pass through a sequence of sleep states—light sleep, deep sleep and REM (rapid eye movement) sleep—that repeats approximately every 90 minutes.