单项选择题
A.bring the sails parallel to the wind
B.reduce sail area exposed to the wind
C.allow the sails to catch more wind
D.remove all tension on the main and jib sheets
单项选择题 When a tornado moves over the water from land it is called a（）.
单项选择题 Wen a hurricane passes over colder water or land and loses its tropical characteristics，the storm becomes a（n）（）.
单项选择题 When a hurricane passes into high latitudes over colder water and the source of heat is disrupted，the storm assumes the characteristics of（）.