look he is （writing） a letter to hislook he is （writing） a letter to his mother这句话为什么添加ing,急,

分类: 作业答案 • 2022-02-18 09:51:00

问题描述：

look he is （writing） a letter to his
look he is （writing） a letter to his mother这句话为什么添加ing,急,

答

因为be doing 而且有look说明现在进行式