Unit 4
一. if 条件句
if可以引导真实条件句和虚拟条件句。真实条件句表示在假设的条件下，能够实现的情况。在这种情况下，主句和从句的谓语动语随各自的人称和时态发生变化，同时if条件句遵循“主将从现”的原则，即主句用一般将来时，从句用一般现在时表将来。
If it doesn’t rain tomorrow, we will go for a picnic. 如果明天不下雨，我们去野餐。
如果if条件句用来描述说话人认为与事实相反的内容，或仅是一种愿望，假设、猜测等，我们称为虚拟条件句。
If I got rich , I would travel around the world. 如果我有钱了，我将周游全世界。
二.虚拟语气
区分条件从句主句例句
★与现在事实相反If+主语+过去
式（be多用
were）…
主语+would/should/could/
might+动词原形…
If I were rich, I would
buy a big house. 如果我
有钱，我将买一所大房
子。
与过去事实相反If+主语+had+
过去分词…
主语
+would/should/could/might+
have+过去分词…
If I had read this article
earlier, I would not have
made this kind of
mistake.如果我早读过这
篇文章，我就不会犯这
样的错误了。
与将来事实相反If+主语+过去
式（be多用
were）
/should+动词
原形/were to+
动词原形…
主语
+would/should/could/might+动
词原形…
If it were to rain
tomorrow, the match
would be put off. 如果明
天下雨，比赛就会被推
迟。
三、根据句意及括号中的提示完成句子。
1. —I often get nervous when I have an English class. What should I do?
—If I were you, I . (ask the English teacher for help
2. —What would the earth be like if there ?(is no air or water on it
—It could be like the moon without any living things.
3. If it ,the crops would be saved. (is to rain tomorrow
4. If we had found him earlier, we .(solve the problem more easily
5. If I hadn’t been so busy, I .(take part in the party
四、单选。
( 1. If my father here now, he tell me what to do.
A. were, would
B. were, will
C. is would
D. is will
( 2. If I a bee, I work much harder.
A. were, would
B. were, shall
C. had, will
D. have, should
( 3. If I much money, I buy a house.
A. have, will
B. had, would
C. had, will
D. have, should
( 4. He learn more quickly if he harder.
A. will, work
B. would , worked
C. would, work
D. will, worked
( 5. If I you, I do that.
A. was, wouldn’t were, wouldn’t C. am, won’t D. were, won’t
( 6. It’s quite impossible that it will rain tomorrow. But if it ,I would still go to the park.
A. should rains
B. would rain
C. rained
D. had rained
五、汉泽英
1. 如果我是你，我会帮助她。If I you, I her.
2. 如果我以前去过那个地方，我就认识路了。（和相反）If I to the place before, I the way.
3. 万一你明天迟到了，我们就不等你了。（和相反）
If you tomorrow, we for you.=If you late tomorrow, we for you.
4. 如果没有空气，地球上就不存在生物。
If there no air, there no living things.
