I use a clock to wake me up because at six o'clock each morning the train es by my house.
A. couldn't
B. mustn't
C. shouldn't
D. needn't
网友回答
A. couldn't
B. mustn't
C. shouldn't
(答案→)D. needn't
解析：此处考查情态动词，needn’t+动词原形表示：没有必要做某事。句意：我没有必要用闹钟唤醒我，因为每天早上6点火车都经过我的房子。
【考点定位】考查情态动词的用法。