when do they come?与when they will come?有什么不同,为什么同样是情态动词位置不一样

when do they come?与when they will come?有什么不同,为什么同样是情态动词位置不一样 when did they come? 什么意思 I don't konw when exactly they will come.P_,they will come t when will you be back 可不可以把be换成come?为什么?有什么不同? 改错 I don’t know when will they come when the firnen come they will ( )the fire quickly Do you know fish come of eggs when they are Do you know when he comes?与When he will come.哪个正确,用法上有什么区别? They don't know when Mr li_____ 这里为什么用will come when they will come has no been announce中为什么要加been? 这里“when they come ”做句子的什么成分 When can they come ( ) home?-Tomorrow evening.