单项选择题
A.notify the competent authorities
B.sound the alarm
C.have passengers put on life preservers
D.cut off air supply to the fire
单项选择题 If two sailing vessels are running free with the wind on the same side, which one must keep clear of the other?（）.
单项选择题 If your weather bulletin shows the center of a low pressure area to be 100 miles due east of your position, what winds can you expect in the northern hemisphere?（）.
单项选择题 In 1979 an extensive（）program was in progress throughout Suez Canal.