比較狀語從句：
　　than, as…as…，not so as…，（not) the same as, the+比較級；
　　eg：Light travels fast than sound.
　　the+比較級：
　　eg：The sooner，the better.
　　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（預言) becomes self- fulfilling, trapping women in a vicious circle (惡性循環) of neglect.
　�。�1）當……的時候：while, when, as ；
　　when：強調一件事情正在發生的時候，另外一件事情突然發生；
　　eg：When I was watching TV, my mother came back.
　　while：強調兩個動作同時進行，一邊……一邊……；
　　eg：My father is cooking while my mother is reading newspaper.
　　as："隨時間推移"
　　eg：As time went by, the days became longer and longer.
　　（2）一……就……：as soon as ,主將從現；用directly，immediately, instantly連接兩個句子；一些名詞如the minute，the moment, the instant也可表示；no sooner… than, hardly… when后面的句子需要倒裝；
　　eg：I will write to you the moment/minute I arrived in Paris.
　　（3）特殊單詞：by the time that, every/each time（使用時后面不要再加when）
　�。�4）till＆until：
　�、� 肯定形式表示的意思是"做某事直至某時"，動詞必須是延續性的；
　　否定形式表達的意思是"直至某時才做某事"，一般用until，動詞為延續性或非延續性都可以；
　　eg: I slept until midnight.
　　Wait till I call you.
　　She didn’t arrive until 6 o’clock.
　�、� 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.