单项选择题
A signal indicating Greenwich mean time would be preceded with（）.
A.a code hoist to indicate Greenwich mean time to follow B.the letter G C.the letters GT D.the letter Z
单项选择题 A sign of thunderstorm development is a cumulus cloud（）.
单项选择题 A shipmate suffers a heart attack and stops breathing. You must（）.
单项选择题 A ship having continuous closely spaced transverse strength members is（）.
