高考英语语法专项状语从句一.定义: 在句中作状语的从句就叫做状语从句二.考点透析【考点1】时间状语从句: 由when, while, as, before, after, since, till / until, as soon as等引导eg. I shall tell him the good news when he comes.【考点2】原因状语从句: 由because, as, since, for等引导eg.. He didn’t hear me because he was listening to the radio. ，eg. Since you are free today, you had better show me how to use the computer.【考点3】地点状语从句: 由where等引导eg. Please put the book where it was after you finish reading it.【考点4】条件状语从句: 由if, unless等引导eg.I will come to see you if I have time on Sunday.【考点5】比较或方式状语从句: 由than, as, as if, as...as...等引导eg.. I know you do better than he does.eg.. The old worker runs very fast as if he were a young man.【考点6】.目的状语从句: 由so that, in order that等引导eg.. They set out early so that they could arrive at the station in good time.【考点7】结果状语从句: 由so, so that, so / such...that...等引导eg.. They set out early so that they arrived at the station in good time.eg.. He finished his work so well that the boss praised him in public.【考点8】让步状语从句: 由though / although, even if, whatever, whoever, whenever, no matter what / who等引导eg.. He is in very good health though he is old.eg.. They didn’t stop working even if it began to rain hard.三.应注意的问题:1.时间和条件状语从句中常用一般时代替将来时a. I will go and see a film if I have time tomorrow.b. I will tell the about it as soon as he comes back.c. He said he would go out for a walk when he finished his work.2.状语从句中可有省略: 在一个含有状语从句的复合句中, 如果主句和状语从句的主语相同, 或状语从句的主语是it, 并且状语从句的谓语含有be动词时, 可以将状语从句的主语和b e一起省略掉a. As (she was ) a child, she began to learn English.b. If ( he was ) alive, he must be at least ninety years old.c. Although ( he was ) told to stop, he kept on working.d. If ( it is) necessary, ring me up.e. He didn’t say a single word until ( he was ) asked.3.as和than引导的比较状语从句中, 从句中和主句中相同的部分往往省略, 从句中只剩下比较对象a. He is a head taller than I ( am tall ).than之后的人称代词是主格或宾格时, 有时意思不同, 如:a. She likes the dog more than me.=She likes the dog more than she likes me.她喜欢狗比喜欢我更多b. She likes the dog more than I.=She likes the dog more than I like the god. 她比我更喜欢狗4.含有no sooner…than…和hardly / barely / scarcely …when…的句子相当于含有as soon as…引导的时间状语的句子. no sooner或hardly放在句首时, 主谓要部分倒装a. He had no sooner seen the policeman than he ran away. =No sooner had he seen the policeman than he ran away. =He ran away as soon as he saw the policemen.b. He had hardly sat down when the telephone rang. =Hardly had he sat down when the telephone rang. =The telephone rang as soon as he sat down.5.immediately, directly, instantly等词也可以作为连词引导时间状语从句, 相当于as soon as引导的时间状语a. I went to see him immediately I heard from him. =I went to see him as soon as I heard from him.6.the moment, the minute, the second，t引导时间状语从句, 相当于as soon as引导的时间状语a. He let out a cry the moment he saw the snake.=He let out a cry as soon as he saw the snake.7.each time, every time, any time, last time, next time, first time可以引导时间状语从句a. They shake hands with each other each time they meet.8.since引导的时间状语从句中, 若谓语动词是延续性动词或状态动词, 则其过去时表示动作的完成或状态的结束a. It is five years since he lived here. 他不住这里己有五年了a. They shake hands with each other each time they meet.9.in case引导的状语从句根据语境的不同，in case既可表示“如果”“万一”，引导条件状语从句；也可表示“以防(万一)”，引导目的状语从句。
下面两道真题均选in case：1. Leave your key with a neighbor ______ you lock yourself out one day. (北京卷)A. ever sinceB. even ifC. soon afterD. in case2. My parents live in a small village. They always keep candles in the house ______ there is a power cut. (重庆卷)A. ifB. unlessC. in caseD. so that10.before引导的状语从句尤其要注意“it+be+一段时间+before…‖这一句型。
如：1. The field research will take Joan and Paul about five months; it will be a long time ______ we meet them again. (安徽卷)A. afterB. beforeC. sinceD. when2. He was told that it would be at least three more months ______ he could recover and return to work. (江西卷)A. whenB. beforeC. sinceD. that11.when引导的状语从句对于when的用法，同学们最熟悉的是表示―当……的时候‖。
如：—Where’s that report?—I bro ught it to you ______ you were in Mr. Black’s office yesterday. (北京卷)A. ifB. whenC. becauseD. before【解析】答案选B。
将四个选项逐一填入空格处，只有填when时，意思最通顺。
句意为：当你昨天在布莱克先生办公室时我就带给你了。
但是when还有一个用法，就是表示―既然‖。
如：Why do you want a new job ___D___ you’v e got such a good one already?A. thatB. whereC. whichD. when还有一点也需注意，就是when表示“这时(突然)‖的用法。
如：1. I had just stepped out of the bathroom and was busily drying myself with a towel ___B___ I heard the steps. (湖南卷)A. whileB. whenC. sinceD. after2. He was about halfway through his meal ___C___ a familiar voice came to his ears. (辽宁卷)A. whyB. whereC. whenD. while11.unless引导的状语从句unless的意思是“如果不……”“除非”，对于涉及unless的考题，一般只要能读懂句意，弄清语境，一般不会有问题。