i often hear this song_____(sing),but i have never hear her____(s_英语解答

i often hear this song_____(sing),but i have never hear her____(sing) it. 下面还有
Listen!you can hear her____ it now.这三个空怎么填,讲一下为什么

人气：345 ℃　时间：2020-02-08 18:27:59

解答

sung被动,sing主动,且表示频率,singing主动,且表示正在发生