（）is the most visible signal of distress from a lifeboat at sea in the daytime.
举一反三
- 163．When using a hand held smoke signal from a lifeboat, you should activate the signal __.
- 79. A distress signal ________.
- How should the lifeboat sea painter be rigged?（）
- Prior to lowering the lifeboat，the most important item to check is the（）.
- What following is not among the functions of SOLAS ships?（） A: receive shore-to-ship distress alerting B: transmit ship-to-shore distress alerting C: receive message for public correspondence D: transmit and receive locating signal