单项选择题
When a wind is permanently changing the direction from which it blows, it is（）.
A.variable B.changing C.backing D.veering
单项选择题 When it is advisable to remain on VHF channel 14 you should say（）.
单项选择题 （）is the most liable to spontaneous combustion.
单项选择题 （）my knowledge the figure at the loading port is not quite accurate.
