开动掘进机前,必须做到以下要求中的()时,才能开动掘进机。
A.有专人放哨
B.必须发出警报
C.铲板前无人
D.截割臂附近无人
参考答案:B, C, D
动词应用。
根据句子,用所给动词的适当形式填空。
1. Everyone in our class________ (like ) reading English in the morning.
2. Meimei ________(study)300 English words since ( 自从) she started to learn English.
3. Be quiet! Someone________ (sleep) in the next room.
4. Tom's mother asked him ________ (do) his homework.
5. Let's ________ (learn) the twelfth Lesson.
6. May I ________ (leave) now?
7. There________ (be) a sports meeting next week.
8. Which one would you like________ (choose)?
9. The little boy stopped________ (cry) when he can't see his mother.
10. Li Ming _______ (buy) an English book last Sunday.
轨道车通过的最小曲线半径不小于140m,并能在()的曲线半径上进行摘挂作业。