答案:Because electromagnetic waves may make electronic devices fail to work. /
Because electromagnetic waves may cause a plane crash.
句意:为什么不能在飞机上使用手机?
根据第五段第2-4行:
Hospitals and airplanes have many electronic devices. When electromagnetic waves try to go through them, they sometimes stop working. A heart monitor could fail to work properly. A plane could crash.
医院和飞机上有很多电子设备。当电磁波试图穿过它们时,它们有时会停止工作。心脏监测器可能无法正常工作。飞机可能会坠毁。
可知答案为:Because electromagnetic waves may make electronic devices fail to work. /
Because electromagnetic waves may cause a plane crash.