两个锐角可以拼成（　　）

A．一个锐角

B．一个直角

C．一个钝角

D．锐角、直角、钝角都有可能

根据下列句子的意思及所给单词的首字母或汉语提示，写出各单词的正确 形式。每空限填一词。

1. Science is one of my favorite s_____. How about you?

2. — Could you give me some a_____ on how to learn English well? 

    — I'd be glad to.

3. Doctors w_____ us to wash our hands before meals to keep disease away.

4. The more we get together, the _____ (快乐) we will be.

5. So far, we've _____ (成功) in saving thousands of people in danger.