29.___ it be Li Ping who broke the glass?No.It __ be Wang Hai whodid it.分析为什么选D而不选B.30.When the old man was alive,he__ sit for hours at the door.为什么选A而不选C.32.I have decided to take the job and I ___ change my mind.A.must not B.can not C.won not D.may not 分析为什么选C而不选B.29，a,could may b,can can c,may must d,can must
问题描述：
29.___ it be Li Ping who broke the glass?No.It __ be Wang Hai who
did it.分析为什么选D而不选B.30.When the old man was alive,he__ sit for hours at the door.为什么选A而不选C.32.I have decided to take the job and I ___ change my mind.A.must not B.can not C.won not D.may not 分析为什么选C而不选B.
29，a,could may b,can can c,may must d,can must
答
29 must be表示肯定的推测 can be/can't be用在疑问句，否定句中，表示疑问否定的推测
30没选项。。。
32won not表示一种意愿，决心
答
29can be表理论上有可能
must be 表肯定猜测
30would过去总是做某事
32won't不会,强调主观意愿和决心（can not 不可能,否定猜测）