用括号内所给单词的适当形式填空。

1.  Where can I buy some______(write) paper?

2.  The toy department is on the______(five) floor.

3.  I don't like to take the bus in the morning.  It's very______(crowd).

4.  He decided______(build)a school for the poor children.

5.  Peter prefers______(hang) out with his friends on weekends.

当离心泵吸入口（）汽化压力的能量数值，降低到正好等于液体的动压降时，叶轮内开始发生汽蚀。

A.低于

B.等于

C.超过