单项选择题
A survival craft being used to pick up a person who has fallen overboard from a vessel should approach the person（）.
A.at a high rate of speed B.under oars C.against the wind D.with the wind
单项选择题 A snag or other underwater obstruction may form a（）.
单项选择题 A shipmate suffers a heart attack and stops breathing. You must（）.
单项选择题 A shipmate chokes suddenly，cannot speak，and starts to turn blue. You should（）.
