单项选择题
What is the purpose of a striker plate? （）
A.Provides surface for applying force on machinery B.Provides landing surface for the sounding bob C.Absorbs machinery vibration D.Prevents valve stem over-travel
单项选择题 What is NOT used as a stern tube bearing，on a large vessel? （）
单项选择题 What best describes the structure from which Stratford Point Light is shown?（）
单项选择题 Upon underwater（）by divers，there are no apparent（）on the bottom plates of the said vessel.
