句型转换。

1. Call him back! (改写为否定句)                

    ________ ________ him back!

2. There will be more roads in our town.(改写为一般疑问句)

    _____   _ there ____    __ more roads in your town?

3. They must not sweep the floors today.(对划线部分提问)    

    _______ ________ they sweep the floors?

4. Going to bed early and getting up early will keep you active in the daytime.(改为同义句)

    Going to bed early and getting up early will keep you active ________ the ________.

5. 我们的英语老师擅长讲笑话.(完成译句)

    Our English teacher    ___ well ____   _ telling jokes.

氢原子的部分能级如图所示，氢原子吸收以下能量可以从基态跃迁到n=2能级的是（　　）

A．10.2 eV

B．3.4 eV

C．1.89 eV

D．1.51 eV