单项选择题
Should the vessel have no deratisation certificate at the time of her delivery，she（）be held to be unseaworthy.
A.shall B.should C.may D.would
单项选择题 Proper use shall be made（）radar equipment if fitted and operational.
单项选择题 Keep clear（）the buoy.
单项选择题 In the International Code of signals，a group of three letters indicates（）.
