Danny is talking to the man beside ____________. [ ]
A. him
B. he
C. they
答案:A
斗轮堆取料机前进不得超过轮斗的()。
A.1/3
B.1/2
C.2/3
下列氨浓度在爆炸范围的有()
A、15%
B、20%
C、25%
D、30%