读一读，填一填。

     Old Peter likes travelling. He travelled to a lot of places in the world. One summer he took his son, little

Peter to London. They travelled by train. It was the first time that little Peter took a train. He was so excite

-d that he sometimes put his head out of the window. He wanted to see the beautiful things along the railwa

-y. Old Peter said," What are you doing, my son? Don't put your head out of the window. It's dangerous

to do that." Then little Peter felt a little unhappy.

1. _____ likes travelling.

2. Little Peter travelled by train for _____.

3. Little Peter sometimes _____ to see outside.

4. It's _____ to put his head out of the window.

住宅或商场等地发生火灾，消防人员用高压水枪灭火，水在灭火中的主要作用是[ ]

A. 降低可燃物的着火点                    

B. 使大火隔绝空气中的氧气

C. 降低温度到燃烧物着火点以下            

D. 水分解出不能助燃的气体