6.I often hear her__A_this song in the classroom after class.

问题描述:

6.I often hear her__A_this song in the classroom after class.
A.sing B.to sing C.singing D.sings
“我经常放学后在教室里听见她正唱着这首歌”怎么不对了
为什么要选A

hear sb. do sth表示听到某人做了某事(表示做了或 经常做)
hear sbdoing sth.表示听见某人正在做某事(表示正在进行)