单项选择题
An aircraft has indicated that he wants you to change course and follow him. You cannot comply because of an emergency on board. Which signal should you make?（）
A.Fire a red flare at night or a red smoke signal by day B.Send the Morse signal N by flashing light C.Make a round turn (360°) and resume course D.Make an S turn (hard right then hard left) and resume course
单项选择题 An advantage of a dry chemical over a carbon dioxide fire extinguisher is its（）.
单项选择题 An ABC dry chemical fire extinguisher would be LEAST effective against a fire in（）.
单项选择题 All portable fire extinguishers must be capable of being（）.
