We need to learn __________ be polite when we make requests.
a. what to  b. why to  c. how to  d. whether to

Let’s go to Beijing ______ the Great Wall.

I really don’t know____________.

—It’s necessary ____ our environment(环境).  —I agree with you.

This is a new CD ______“Best Friend”.

I don’t know ______ a show. Can you tell me?

Why ____________ enjoy Beijing opera with us?

There are so many delicious food in the menu. I can’t decide ________.

Bridge Street is a good place _______.
A. have fun    B. to have fun   C. having fun    D to having fun

---What should we do to fight A/H1N1 flu?
---We should wash hands often, avoid ______ to crowded places and so on.