A distress signal（）.

A.consists of 5 or more short blasts of the fog signal apparatus

B.may be used separately or with other distress signals

C.consists of the raising and lowering of a large white flag

D.is used to indicate doubt about another vessel's intentions

工程开工前监督准备工作包括（）。

A、审查勘察设计图纸

B、确定质量监督工程师

C、制定质量监督工作方案

D、检查工程建设各方主体质量行为