单项选择题
The speed at which a storm centre moves is the（）.
A.speed of movement B.speed of advance C.speed of storm D.storm movement speed
单项选择题 The speed of a vessel adjusted to that of a pilot boat at which the pilot can safely embark is（）.
单项选择题 The step of a pilot ladder which prevents the ladder from twisting is the（）.
单项选择题 The term of landfall means（）.
