问题详情：
![---Doyouknowthereason]( "---Doyouknowthereason")
--- Do you know the reason _________ pilots turn off the plane’s lights before taking off?
---The practice is for the passengers to adjust to the dark _________ an emergency.
A．why; for fear that B．for which; in case of
C．how; for fear of D．that; in case
【回答】
B
知识点：介词
题型：选择题
