I heared him sing that song yesterday.中sing为什么不改变形式?

I heared him sing that song yesterday.中sing为什么不改变形式? we heared him sing the song in the next room 改为被动语态 I often hear him _____ ( sing ) in the next room. I tired to call you __ I heared from him ,but you were not in .A.since B.while C.until D.as soon as I often hear him ( )the pop songs .A sing B sings C singing D to sing The villagers had many trees ___ ( plant ) just then .They managed to make themselves ___ ( understand ) in very simple Eng .I heard the song _____（sing） in English .I heard her ___ (sing) the song in Eng.I saw him ___( open )the window .I saw th I heard him singing改为被动语态which is correct?then I heard him sing? know of 的用法know 和 know of 用法的区别.i know him.和i know of him 有什么差别吗?类似的还有hear.和hear of .比如说i heared the voice和i heared of the voice有什么不一样的地方,在用法上有什么不同.什么样的 I saw him __________(Sunday,May 4th) Just then I heared a noise.(保持原意）Just at_____ ______I heared a noise I'm so depressed when I heared this I often hear him sing the same song被动语态He ____ often ____ ____ sing the same song. I heard him ____ (sing) when I passed his room该填什么?为什么这样填? 1、When I passed his room,I heard him （）（sing） the,morning,I ,him,sing ,heard,song ,this .连词成句. I often hear him sing the song in the room.变为被动语态 I often hear him（）in the next room.（sing） I often hear him _____ ( sing ) in the next room.为什么答案上要求加ing?