人教版八年级英语上主将从现.doc

八年级上语法专项----主将从现
S 一、如果主句是将来时或表示将来含义时，那么条件和时间状语从句多用一般现在时
如： When I grow up, I will be a nurse and look after patients/ I want to be a nurse and look after patients.
我长大后要当一名护士，照顾病人。
S二、如果主句是祈使句，那么从句通常要用一般现在时
如：Don’t laugh at me when I make a mistake.
我犯错误的时候不要笑话我。
S三、如果主句是含有情态动词的一般现在时，根据需要从句多用一般现在时
如：You should be quiet when you are in the reading room
在阅览室时应保持安静。
SS四、主将从现说的是在含有时间状语从句和条件状语从句的主从复合句中，如果主句的时态是一般将来时，那么从句要用一般现在时。
例如：I will tell him about it when he comes.
If it is fine tomorrow, we will go outing.
五、如果主句的时态是过去将来时，那么从句要用一般过去时 。例如：
He said that he would have another try if he had the chance.
I knew he could help me if he was free the next day.
S主要标志有：if 、unless 、until、 when 、as soon as等
S注意if 条件句的时态搭配：
1．if从句用一般现在时，主句用一般将来时
If he runs he’ll get there in time. 如果他用跑的，他就会及时赶到那儿。
The cat will scratch you if you pull her tail. 如果你拉猫的尾巴，它就会抓你。
2．if从句用一般现在时，主句用may/might/can
If the fog gets thicker the plane may/might be diverted. 如果雾在大一些，飞机可能就会改在别的机场降落。
If it stops snowing we can go out. 如果雪停了，我们就可以出去。
3．if从句用一般现在时，主句用must/should
If you want to lose weight you must/should eat less bread. 如果你想减肥，你必须少吃面包。
4．if从句用一般现在时，主句用一般现在时
If you heat ice it turns to water. (也可用will turn)如果把冰加热，它就会化成水。
4．if从句用现在进行时，主句用一般将来时
If you are looking for Peter you’ll find him upstairs. 如果你是在找彼得，上楼就会找到他。
if引导的条件状语从句专项练习
Ⅰ.单项选择
（ ）1.If you _____ to the party, you’ll have a great time.
A. will go  B. went  C. go   D. going
（ ）2. I ____ her the answer if she ____me.
A. can tell, will ask   B. will tell, will ask 
C. would tell, ask   D. will tell, asks
（ ）3. – What are you going to do tomorrow?
  --We’ll go to the library tomorrow if it ___.
A. isn’t rain  B. rain   C. won’t rain  D. doesn’t rain
（ ）4. What will you do if you _____ to the old folk’s home?
A. go   B. went   C. going   D. will go
（ ）5．I’ll give the book to him if he ___ here next Sunday.
A. will come   B. comes   C. is coming    D. came
Ⅱ.用所给词的适当形式填空
6..If you ________(feel) tired, you _______________ (have) to have a rest.
7. Where _______ he _________(see) the film if he ________________(have) time?
8. If there __________(be) fewer trees, there _______________( be) more pollution.
9. If Marcia _____________(live) alone, she ___________________( keep) a pet parrot.
11. Lana ________________( buy) a new dress if the old one ____________(be) out of style.
12.The twins ______________(fight) if they_______________(argue).
13. I ____________(have) a bake sale if I _____________(need) money for education.
14. Peter _____________( send) me a beautiful souvenir if he ________________(tour) Spain.
15. I ____________(go) to the beach if it________________ ( not rain) this week.
17. __________they __________( have) a match if the P.E. teacher _____________(be) busy?
18. If she ____________(get) up late, she _____________ ( not catch) the early bus.