why (not) do

这里应该牢记:why(not)只能跟不带 to 的不定式。why not do 这个结构常常用来表示建议：

1. Why not try to train your character? (Mis) 为什么不努力去锻炼自己的性格呢?

2. Why not wait till the winter sales to buy a new coat? (LEG) 为什么不等到冬季大甩卖时再买一件新外衣呢?

这是各类考题经常考核的一个项目：

1. ——It's a long time since I saw my sister. ——her this weekend? A. Why not visit B. Why not to visit C. why not visiting D. Why don't visit(全国高考卷 I,07-24)

2. Why not $\$frac{to}{A} wait for a couple of days? D B C for A

3. Why to worry about such trifles? A B C D

4. You are putting on weight. Why not ____ your milk without sugar? A. have B. you have C. having D. for you to have

5. Why ____? It's not very important.

A. to worry B. worry C. you are worried D. you worry(Nelson, 300C)

6. ____ him tomorrow?

A. Why not to call on B. Why don't call on

C. Why not calling on D. Why not call on(全国英语专业四级,01-43)