随着瓦斯浓度的增高,煤尘爆炸下限浓度会(),煤尘爆炸的上限也会(),爆炸的浓度范围扩大
A、下降,下降
B、提高,提高
C、下降,提高
D、提高,下降
参考答案:C
—Could you tell me how to get to the People's park?
—______.[ ]
A.No,I couldn't
B.No,I can't
C.Sorry,I couldn't
D.Sorry, I don't know
事故调查组应当自事故发生之日起( )天内提交事故调查报告。
A.15B.30C.45D.60