单项选择题
A.warmer，less dense，and less stable
B.cool，more dense，and drier
C.muggy and cloudy
D.extremely moist with high relative humidity
单项选择题 Commercial ships or other persons or agencies requiring the assistance of Canadian Coast Guard icebreakers should first contact（）.
单项选择题 Coiling new rope against the lay，bringing the lower end up through the center of the coil，then coiling with the lay，in order to remove the kinks，is known as（）.
单项选择题 Coast Pilots and navigational charts are kept corrected and up-to-date by using the（）.