③主句为祈使句，if从句用一般现在时态。
Don’t jump into the river if you feel very hot.如果你感到很热，不要跳入河里。
④主句为过去将来时，if从句用一般过去时态（如果涉及到be动词，一律都用were）。此时，表达的是和现实相反的推测，用虚拟语气。
If I were you, I wouldn’t do it like that.
if引导的条件状语从句
用法
例句
①主句为一般将来时态，if从句用一般
现在时态（即主将从现）。
We will stay at home if it rains tomorrow.
如果明天下雨，我将要呆在家。
②主句中含有情态动词，if从句用一般现在时态。
If you finish your homework, ห้องสมุดไป่ตู้ou can go home now.如果你做完了作业，你现在可以回家了。
2. If it ________（not snow）tomorrow, we will feel unhappy.
3. You mustn’t go to school if you ________（be）still in bed.
4. If he _______（be）at home at that time, he would know it.
5. Please show me the way if you ________（know）it.
6. You will hurt your teeth if you ________（eat）too much candy.
7. If you gave me a toy car, I _________（be）very happy.
8. I would get the prize if I _________（work）hard.
如果我是你，我就不会那么做的。
If you gave me some money, I would be very happy.如果你给我一些钱，我就会很高兴的。
【边学边做】用括号内所给词的正确形式填空。
1. What will you buy if you ________（have）a lot of money