下列命题中，正确的命题有几个（　　）

①垂线段最短；②同旁内角互补；③相等的角是对顶角；④过直线外一点有且只有一条直线与已知直线平行．

A．1个

B．2个

C．3个

D．4个

句型转换。

1. It's about five kilometers from my home to the school. (对划线部分提问)

    _____ is it from my home to the school?

2. My sister does her homework in the evening.(改为一般疑问句)

    _____ your sister _____ her homework in the evening?

3. I think Mr. Chen is in London. (改为否定句)

    I _____ Mr. Chen _____ in London.

4. The two boys want to travel. (改为同义句)

    The two boys want to _____.

5. He works in a factory. (对划线部分提问)

    _____ he _____?