单项选择题
A.go B.going C.gone D.went
When a ship is in port, （）must keep a gangway watch.A.o...
单项选择题When a ship is in port, （）must keep a gangway watch.
A.officers B.crew members C.sailors D.motorman
When a ship is in port, the sailor on duty （）a gangway ...
单项选择题When a ship is in port, the sailor on duty （）a gangway watch.
A.has B.keeps C.looks D.takes
Hang national flag upside down should be strictly （）.A....
单项选择题Hang national flag upside down should be strictly （）.
A.prohibit B.prohibited C.prohibiting D.prohibits
