兆欧表使用时应放在( )。A．清洁的地方B．大的外电流导体和外磁场C．平稳牢固的地

把多项式a³-a分解因式，下列结果正确的是（　　）

A．a（a²-1）

B．（a+1）（a-1）

C．a（a+1）（a-1）

D．a（a-1）²

（ ）是区别不同税种的重要标志。

A．征税对象

B．税目

C．税率

D．计税依据

用所给动词的适当形式填空。

1. Can you help the students with________ (swim)?

2. My father________(not want) to go fishing.

3. Thank you for________(help) me.

4.What can Mary_________(do)?

5. Tom_________(paint)  pictures for his mother sometimes.

The kite __________ is nice.[ ]

A. on wall

B. in the wall

C. on the wall

D. at wall

The service economy doesn't suggest that we convert our factories into laundries to survive.

A．imply

B．persuade

C．hurl

D．transform