单项选择题
The apparent wind’s speed can be zero only when two conditions are present. One condition is that the true wind（）.
A.must be from dead ahead B.speed must be zero C.must be from dead astern D.must be on the beam
单项选择题 The apparent wind can be zero when the true wind is from（）.
单项选择题 Steam fog is most likely to occur on the Mississippi and Ohio Rivers in（）.
单项选择题 Radiation fog（）.
