这个句子的被动语态：we must keep the classroom clean 谢

这个句子的被动语态：we must keep the classroom clean 谢 We must ask Tom to clean his room again. 把这个句子改为被动语态 谓语中含有动词短语的句子怎么改成被动语态We must take good care of the young trees.怎么改成被动语态? The students must finish their homework this afternoon 改句子把这个句子改成被动语态的 英语.主动语态变被动语态的题.We must plant more trees next year. We must finish our work on time 被动语态 We must finish the work on time 变被动语态 We must finish our work on time 被动语态 We must water the flowers every day.被动语态填空 we must keep our classroom clean改被动语态 初中英语变为被动语态we must keep our classroom clean We must water these young trees ofen.(改为被动语态) we must make some rules.变被动语态 We must do something to help her被动语态 We must do homework every day被动语态 改为被动语态：We must do the work right now 请将下面的句子（主动语态）改为被动语态：We have put off the meeting till next Monday.We must pay more attention to the passive voice of English verbs. 这个句子是主系表还是被动语态?