Listen,the birds ________________ (sing) in the tree

问题描述:

Listen,the birds ________________ (sing) in the tree

Listen, the birds are singing(sing) in the tree

Listen, the birds(are singing) in the tree
听,鸟儿正在树上唱歌
listen 说明事情正在发生(用现在进行时),birds是说明复数用are