过去这儿常有很多鸟儿歌唱.There used to be a lot of birds (----) here.
问题描述:
过去这儿常有很多鸟儿歌唱.There used to be a lot of birds (----) here.
答
singing
过去这儿常有很多鸟儿歌唱.There used to be a lot of birds (----) here.
singing