根据句意和首字母提示写出单词。

1. Tom is very helpful. He often gives his s_______ to the old people on the bus.

2. The flu (流感) is a big p_______ in the world now. We must be careful.

3. We all like our English teacher because she is always w______ to help us.

4. — What do you want to be in the f_______?

    — I want to be a singer because I like traveling.

5. The a_______ by the 15-year-old girl are very popular among the young people now.

下表是某动物毛色遗传实验的结果，请分析并回答问题

（2）丁组的基因组成为下列哪一种组合______

A．AA×Aa         B．aa×aa        C．Aa×Aa          D．aa×AA．