You see a vessel carrying a black diamond which indicates a（）. vessel towing astern。 barge pushed ahead。 vessel towing astern only when the length of her tow exceeds 200 meters。 this signal does not exist in international water。
产品开发是一个从（）开始到制造出产品为止的全过程。
母线差动保护因故停用，一般应如何处理？
You hear the fog signal of another vessel forward of your beam.Risk of collision may exist.You MUST（）. Reduce speed to bare steerageway。 Stop your engines。 Begin a radar plot。 All of the above。
在投入母线电流差动保护前，怎样检查其交流电流回路接线的正确性？
电源内阻很大，宜采用（）
