I often hear John (sing/singing/to sing)in his room.为什么这里要填sing

I often hear John (sing/singing/to sing)in his room.为什么这里要填sing what's your ----sport,john?I often ----soccer at school ,---I like volleyball best. I often do sport( )John.怎么做? 三个英文单词的区别jailprisonpenitentiaryAny difference?i often hear people say these three alternatively.but i really wanna know the distinction among them.i want somebody's help! look keep built be feel listen sleep call hear go i find it not easy_____ wellthe boy john ofeten goes to school by carshe often birds sing in the tree where are you to beijing I often hear the little girl___(cry)in the morning I often hear him _____ ( sing ) in the next room. i often hear her sing a song变被动句 i often hear jim ----（play）violin at home I often hear the song _____on TV.（sing） I often hear him ( ) in the room I often heard him ( ) in the room that's all I hear you ——John had an accident on his way home yesterday.——( )A.really?it's so cool!B.it's up you.C.i'm sorry to hear that .D.that's all right. I often hear her （）in her room . Ato sing BsingingI often hear her （）in her room .Ato singBsingingCsingDsings I often hear him paly the piano at home.里面的那个play啊..为什么不要-s啊?!him不是第三人称单数么?!这样写什么意思啊?! Do you often hear John ______ in his room? Listen ! now we can hear him ____in his roomGive me a reason ------Do you often hear John ___in his room?----Listen,now we can hear him ____in his room .%Dª singing,singingB sing,singingC to sing,singing whose computer doesn't work ( ),I think .A.john has B.John does C.john D.John's