She didn't answer the phone.She be asleep.A. couldn'tB. mustn’tC. mightD. had to

问题补充：

She didn answer the phone.She be asleep.

A. couldn

B. mustn’t

C. might

D. had to

答案：

A. couldn

B. mustn’t

(答案→)C. might

D. had to

解析：might也许; couldn 意为:不可能; mustn’t意为:不可以/一定不; had to意为:不得不,必须.