when they will come has no been announce中为什么要加been?

改错 I don’t know when will they come when the firnen come they will ( )the fire quickly 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 they come home,they will go to bed.这句话哪里错了? Could you tell me---?A.when will they leave Beijing.B.when could they leave BeijingC.when they will leave BeijingD.why she did't come to school 对in two weeks提问应该用when还是how long例如:They will come back in two weeks.提问应该是非功过How long will they come back?还是when will they come back? When do they come home? When will she come back? When will she come back when will u come here When will we come here? When he will come back when they will come has no been announce中为什么要加been? I don't konw when exactly they will come.P_,they will come tomorrow morning.如题 答案应该是什么 我单词不怎么熟悉 when will they, when they will的区别和用法 When will they come here ? I really don't know .(合并为一句)I really don't know when __ __ come here . We don't care about ___ they will not come tomorrow.A.whether B.that C.if D.when When will he come to see you?