相关考题
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单项选择题
You should keep national flag（）.
A.flying
B.flew
C.flown
D.flies -
单项选择题
You should slack the mooring lines （）when the wind is big.
A. at the same time
B. on time
C. in time
D. at times -
单项选择题
We must （）to inspect the problems about the safety of fire prevention.
A.prepares
B.preparing
C.prepared
D.prepare
