问题补充：
Ladies and gentlemen, please fasten your seat belts. The plane .
A. is taking off
B. takes off
C. has taken off
D. will be taken off
答案：
(答案→)A. is taking off
B. takes off
C. has taken off
D. will be taken off
解析：时态题。“先生们女士们，请系紧好安全带，飞机即将起飞。”is taking off用现在进行时表将来。
