You must be home at half past ten.为什么中间要用BE,而不是具体的BE动词（are）,

you must be home at half past ten. You must be home at half past ten.和 You must come home at ha you must be home at half past ten.是否也可以you must come home at you must be home at half past ten.为什么不用come? 英语问问问you must be home at half past ten 这个句子 中的be 我可不可以理解为：ho You must be home at half pass ten.可以以把be改为come吗? 一.You mustn't come home late. You must be home at half past 1 you mustn't come home late.you must be home at half past t 英语must be学了新概念第一册一课,如下课文,you must be home at past half eleve you mustn't be home at half past ten这句中的be是什么意思,可否不加?I can't You must be home at . you must be home at