火花塞间隙过大,发动机易出现()。
A.低速断火
B.高速断火
C.怠速不稳
D.怠速熄火
参考答案:B
E-mail is very popular today. People seldom write letters now,_______?
A.did they
B.do they
C.didn't they
D.don't they
HSE管理体系的十要素是什么?