目前我国环境影响评价等级分为（）级评价。
A.二
B.五
C.三
D.四
参考答案：C
The government has___________a series of policies and measures to ensure the improvement in living standards.
A．put out
B．put off
C．put forward
D．put down
减压器的作用有：（）
A.减压
B.稳压
C.隔绝火焰
D.防止回火
