目前我国生产性粉尘的卫生标准有______，总粉尘浓度和呼吸性粉尘容许浓度。

A．时间加权平均容许浓度

B．工人接触时间肺总通气量

C．粉尘浓度超标倍数

D．最高容许浓度

用适当的介词填空

1. There are some books              the desk.

2. The hotel is next             the bank.

3. Betty sits             Tony's right.

4. Class One is in front of Class Two,Class Two is             Class one.

5. There are sixty minutes(分钟)              an hour.

6. I live              23 center street.

7. The library is               the market and the shop.