单项选择题
All of the following are distress signals under the Rules EXCEPT（）.
A.a green star signal B.orange-colored smoke C.red flares D.the repeated raising and lowering of outstretched arms
单项选择题 What is NOT a distress signal?（）.
单项选择题 What would NOT be a distress signal?（）.
单项选择题 When two vessels are in immediate danger of collision，the stand-on vessel must（）.
