单项选择题
The type of fog that occurs on clear nights with very light breezes and forms when the earth cools rapidly by radiation is known as（）.
A.Radiation fog B.Frontal fog C.Convection fog D.Advection fog
单项选择题 The two vessels underway may collide with（），if they don’t take immediate measures.
单项选择题 The term restricted visibility，when used in the Rules，refers to（）.
单项选择题 The term PROLONGED BLAST refers to（）.
