she was often heard in her own garden in the morning. a.sing b. to sing c.singsing d.sung
问题描述：
she was often heard in her own garden in the morning. a.sing b. to sing c.singsing d.sung
答
C
不过应该是singing吧
答
C. often 是介词， 后面动词加ing ，就是singing了。
答
c singing be heard doing 被听见正在做……