请问高手must be doing 有被动语态吗 形式是怎么样的

请问高手must be doing 有被动语态吗 形式是怎么样的 Look:Jack is putting on his hat and coat.He must (be going) out.请问这里的be going能否改成go呢?有什么区别呢?结构must+be+doing/coming/joking等must+do/go/know/have等 是must be to do还是must be doing must be do与must be doing 区别 请问高手Material must be AZO DYE free and should comply to REACH standardMaterial must be AZO DYE free ‘must be’后加什么 加doing 请问be worth doing和be worthy of doing有何区别? 请问有没有need to be doing sth这种用法 有be sorry doing 请问be aimed at doing sth.和aim at doing sth.有什么区别? 请问must be和must在用法上有什么不同【举五个例子】 请过路高人谈一下must be doing 与 must have been doing 的用法.这是在新概念第九课出现的.这里的 must 换成 shall 、could 、can 等意义上有什么变化吗? 有没有be bored doing,be bored to do,be bored in doing,be bored in to do?请问有没有这些说法 must be stopped from doing这个词组什麽意思 Attentions must be paid to do sth还是doing sth computers must be of great use to doing scientific research 用must be done 和must be doing 造句再加个 as a result must,must be有什么区别