单项选择题
In order to maintain a safe speed at all times，any necessary alterations of speed must（）.
A.be instantly put on B.be instant put into use C.be instantly put into effect D.be put immediately
单项选择题 In order to detect rot in manila lines，you should（）.
单项选择题 In heavy seas the helmsman should steer the survival craft（）.
单项选择题 In general，the extent of the carrier’s immunity，as laid down by the Act，cannot be increased（）contract.
