Someone is knocking at the door,but who can____ be?

Someone is knocking at the door.____ is it? someone is knocking at the door.It might be the posyman.为什么用is knocking 单句改错：listen!someone is knocking the door 英语翻译sorry，是Someone is knocking _____ ______ the door. Someone is knocking at the door,but who can____ be? listen! someone is knocking _ the window填什么 There is someone knocking at the door.为什么用“knocking”,要加“ing”? Someone is knocking at the door.同义句改写：There is ___ ___ at the door. someone is knocking at the door.who [ ]it be?A;mustB;canCmayD;shall必须有理由 There is someone knocking at the door.It may ________ (be) the postman.如题 someone is knocking at the door.___must be Tom.为什么用he而不用it? someone is knocking on the door.who can____ beA that Bthis Cthe Dit someone is knocking at the door,____ _____?如何变反义疑问句为什么 arent they Someone is knocking at the door._must be TomSomeone is knocking at the door._must be Tom A.that B.It C.He D.This “Someone is knocking at the door,please( )it”he said to me.A close B answer C look D see这题的意思是?knocking是什么意识? Someone is knocking on the door （同意句）改成There is ___ ____ ___ the door Someone is knocking at the door,but who can____ be?A.one B.he C.she D.it 6.There is someone knocking at the door,who _____ it be?A.can B.may C.must D.need