探究一：条件状语从句结构
1._____+if+________________
e.g. You should try it by yourself if you want to know how deep the river is.
I will go to his birthday party if he invites me.
2. _______________，______
e.g. If you go into the river, you will be drowned.
If he invites me, I will go to his birthday party.
探究二：条件状语从句时态
规则1：if引导的条件状语从句，主语含有情态动词can/could/must/should/may/might等时，从句用_________时态。
If it stops raining, we can go outside.
If all your answers are right, you can go to Hainan for holiday.
You may stay to dinner if you like.
规则2：if引导的条件状语从句，表示在某种条件下某事很可能发生时，if从句用___________，主句用____________。
If it doesn’t rain tomorrow, we will have a picnic.
If he runs, he won’t be late for school.
If it rains tomorrow, we will stay at home.
规则3：if引导的条件状语从句，主句是祈使句，从句是__________时态。
Don't wait for me，if I'm late.
Stay at home if it rains tomorrow.
Don't play basketball if you don't finish your homework
规则4：if引导的`条件状语从句，表示在某种条件下某事一定会发生时，if从句用___________，主句也常用___________。
If you put salt into water, it disappears.
If you take a fish out of water, it dies.
If you heat (加热)ice, it turns into water.
探究三：条件状语从句引导词
1. if如果
2. unless除非如果不相当于（...）
3. as long as只要...就...
You won't pass the exam unless you work hard.
As long as you get up early, you will catch the bus.
探究四：同义词转换
1.祈使句+and+简单句 and表顺承“那么”
If you study hard, you will pass the exam.
＝
2.祈使句+or+简单句 or表转折“否则”
If you don't hurry up, you will be late.
＝
ss与...转换
We will go for a picnic unless it rains tomorrow.
＝
探究五：注意事项
1.主句将来时态中多用will,一般不用be going to
2.当if表示是否时,从句不是条件状语从句，而是宾语从句,此时不遵循“主将从现”,从句该用什么时态就用什么时态。
e.g. I don't know if he has come here.
Tom asked if I had read the book.
3.在if引导的条件状语从句中不能使用some，而要用any。
e.g. If you have any questions to ask, please come to my office.
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