when's someone knocked at the door, Jack was making a telephone call.这里面的when's怎么解释啊,这个句子是不是错了啊

It's polite to say sorry when you knock into someone carelessly是什么意思 it's good _(manner)to say sorrywhen you knock into someone. i think someone is in .let's knock the door 这句话的knock为什么要改成knock at She was cocking when she heard someone ( )knock at the door When I was doing my homework ,I heard someone (knock) at the door. i __(read) a history book when someone __(knock) at the door Was it 8o'clock -----you heard someone------at the doorA.when knockingB.when knockC.that knockingD.that knock Was it8o'clock( )you heard someone ( )at the door.a.when; knockingb.when; knockc.that; knockingd.that; knock I think someone is in.Let's knock the door.改错 I think someone is in . Let's knock the door. 改错 Did you hear someone[ ] 【knock】 at the door when you[ ]【 watch】 TV last night.填什么,为什么 knock at,knock onWhat's the differance? Listen:Someone ______(knock) at the door. When happiness knock my When happiness knock my door i was watching tv when i heard the door(knocking)i was watching tv when i heard someone(knocked)at the door两个knock形式对吗? It was almost midnight ( ) she heard someone ( ) at the doorA when,knocking B that ,knocked C when ,knock D that ,knocking WHEN I WAS READING I HEARD SOMEONE -----(KNOCK)AT THE DOOR为什么WHEN后加ING不是在I HEAR后加吗/告诉我规律括号里的也要填!谢谢! When happiness knock my doo