when do we have to be doing the research?有谁能解释一下这个句子的语法吗?特别是"be doing"这里 是什么时态?

When do we have to give______our compositions When do we have to give______our compositions?为什么? The next important question we have to decide is when do we have to submit the proposal.为什么这么改do we have to-----we have to he wanted to know when________ the English partyA.when will we have B.when we will haveC.when would we haveD.when we would have I think it's useless ___ when we have made mistakes.All we can do is to correct themA complaining B complained C having complained D being complained What do we have （ ）dinner?A.TO B.FOR do you know什么at8:00am a：who to talk wath b：when to have a meeting c：when shall we have a md：where can have a meeting Do you know ____ have our summer holiday?next week. A.when we will B.when are we C.when will weD.when we are 1.We are going to have fun______English this term.A.learn B.learning C.to learn D.have learned1.We are going to have fun______English this term.A.learn B.learning C.to learn D.have learned2.She doesn't____to do and when to do itA.what B.how C.that D. We have funWe have fun_____sports.A,do B,doing C, to do D,does What else do we have to do? Do you know_____for advice when we have problems?You can talk to your parents or teachers A wDo you know_____for advice when we have problems?You can talk to your parents or teachersA who to talk B who we can talk C who to talk to D who can we talk t We have put off the get-together until next weekend ______ we won't have so much work to do.A....We have put off the get-together until next weekend ______ we won't have so much work to do.A.which B.where C.that D.when为什么不能选C?那么that when do you think_go hiking?A we shall B we are going to 去年中考英语选择题一道 说明原因 He want to know______the English party.A when will we have B when will we have C when would we have D when we should have what should we do when we have a fever ?/是什么意思 What should we do?when we have the fever ( )do we have chinese this morning?A.who B.what C.when D.how