单项选择题
What does the abbreviation SWL stand for?（）.
A.Signal wave letters B.Ship without light C.Safe water line D.Safe working load
单项选择题 What time can I（）the canal?
单项选择题 What’s wrong（）the winch?
单项选择题 When out of sight of land, a ship’s position can be found by using（）.
