根据句意及单词首字母完成句子。

1. Don’t c      too much about it. It's not good.

2. We should speak English as much as p     in class.

3. The school things i       pens , pencils , rulers and other things.

4. Don't pull the door. P     it, please.

进行成组操作时必须使用主存缓冲区，缓冲区的长度等于( )。

A．平均逻辑记录长度乘以成组块因子

B．最大逻辑记录长度乘以成组块因子

C．最小逻辑记录长度乘以成组块因子

D．逻辑记录长度