用sb must be和can't be doing造句

用sb must be和can't be doing造句 用must be done 和must be doing 造句 can't be 和 must’t be 用there be sb doing sth 造句 can‘t be must’t be区别 用 be doing 和be doing to do 造句 三个 must be,may be,can't be 表推测的意思 并造句 can be,may be和must be 用be+doing 造句^-^ 用英语造句:1.take place 2.see.doing 3.be busy 4.It's 形容词 for sb t 用下列词组造句：1.be doing 2.differentcultures 3.mind doing 4.see sb Can be 和must be的区别