【重点语法】if 引导的条件状语从句
If 引导的条件状语从句的时态与主句的时态
1、主将从现
若主句用一般将来时，则if 引导的条件状语从句用一般现在时，我们称之为“主将从现”。
例如：If he comes, he will bring his violin.
若果他来，他将会带来他的小提琴。
2、主情从现
若主句中含有must,may,can等情态动词，则if引导的条件状语从句也用一般现在时。
If we satrt now, we can finish the work on time.
3、主祈从现
若主句是祈使句，则if引导的条件状语从句同样也使用一般现在时。
Work hard if you want to get good grades.
如果你想取得好成绩，就要努力学习。
注意：有些同学分不清哪是主句哪是从句，一个方法就是紧跟着if的是从句，另外一部分就是主句。
拓展：if 除了可以理解为“如果”，引导条件状语从句，还可以理解为“是否”用来引导宾语从句。
If 引导的宾语从句，主句和从句的时态遵循以下规则
1、主现从任
若主句是现在的某种时态，则if后引导的宾语从句根据实际情况确定。
I don’t know if he will come to school tomorrow.
我不知道明天他是否来学校。
No one tells me if Tom went out last night.
没人告诉我汤姆昨天晚上是否出去了。
2、主过从过
若主句是过去的某种时态，则if 从句也要用过去的某种时态。
Lucy asked Tom if he was afraid of dogs.
露西问汤姆他是否害怕狗。
巩固练习
1、If you want to get good grades, ______ in as much effort as possible.
A. putting B.put C.to put D.puts
2、—— Tina wants to know if you _______ to the park with us tomorrow.
—— I’d love to.But if it _______ , I may go to the library instead.
A. go ; will rain B.go; rains C.will go ; rains D. will go; will rain
答案：1、B 2、C
How to deal with our stress We all have some problems and stress in our lives. How should we deal with them? Firstly, we should take more exercise.Sports can help us to have a healthier body and study better. Secondly, we need to talk with our teachers,parents and friends and try to tell them about our trouble. They may give us some useful advice. Thirdly, we can also listen to music and read books. They are good ways to relax ourselves. Fourthly, we should try our best to study hard and learn to face our grades bravely. Fifthly, if we often have too much stress,we'd better see a doctor. If you do as I tell you, you'll solve your problems easily.