Our headmaster told us that our classroom was so dirty that it mu_英语解答

Our headmaster told us that our classroom was so dirty that it must__clean.
A keep B be kept C been kept

人气：137 ℃　时间：2019-10-19 07:58:33

解答

选B
首先被动语态,排除A
其次,must是情态动词,其后要跟动词原形