层门从地面算起不应低于多少,离地面不得大于多少,净宽度与吊笼进出口宽度之差不得大于()。
A.1.8m
B.0.05m
C.0.12m
D.0.1m
参考答案:A, B, C
The teacher gave back his homework, so he _ do it again. [ ]
A. must
B. had to
C. needed
D. might
就认识层面而言,认识活动可分为()。
A.常规认识
B.基础认识
C.科学认识
D.哲理认识