he was heard singing=he was heard to sing?dictionary tells us like this,I don't know why

he was heard singing=he was heard to sing?dictionary tells us like this,I don't know why I heard he was singing in the next room.是什么从句? he heard that a little girl was singing by the river 改为简单句 I heard he is singing.是病句么?能不能改为I heard that he is singing. He asked me if I often heard Jenny ___________ pop spngs in the next room.A) sing B) to sing C) singing D) was singing选什么?为什么? He asked me if I often heard Jenny ________ pop songs in the next room.A. sing B. to singC. singing D. was singing知道选A,为什么 I heard he was singing in the next room.I heard —— ——in the next room.改为同义句 I singing someone doing heard my honework while was I She heard someone was singing（改为简单句） 为什么这里不要还原to?I heard the boy singing just now.The boy was heard singing just now. Who heard him singing in the next room?(被动语态)_____ _____ ______ he heard singing in the next room? He was often heard ( )in his apartment before,but now,no one can hear him ( ).A.to sing;singB.sing;sangC.singing;singingD.sing;singing并说明一下原因 38.He asked me if I often heard Jenny ________ pop songs in the next room.A.sing B.to singC.singing D.was singing答案是A.为什么 she was heard singing song just now如果有确定的时间,如yesterday morning 是用heard to sing 还是heard singing He was often heard sing .对么 He was heard() out (go)When I was reading a book.he was heard () out.(go) She was often heard ( ) in English.A.sing B.singing C.to sing He was very surprised when he heard the ( surprise) news.