航海英語遇險用語單項選擇題每日一練(2019.01.21)

來源：考試資料網(wǎng)

1 All of the following are distress signals under the Rules EXCEPT（）.

2 The color of rockets，shells，or rocket parachute flares used to indicate that the vessel is in distress and requires immediate assistance is（）.

3 Which signal is recognized as a distress signal?（）.

4 The service life of distress signals must be not more than（）.

5 What is NOT a distress signal?（）