英语成分。i am doing my homework
①am是什么成分
②为什么i doing my homework是错的
③i had doing my homework这样表达对吗?
doing是动名词形式不能单独做谓语,所以必须是am doing构成复合谓语
追问那i had doing my homework对吗?
追答不对
追问为什么?
追答have做动词后面不能直接跟动词的ing形式
这个可以
have been doing可以这么说,但是这个是完成进行时态
追问那 had been 是谓语动词
doing是动名词?
所以一个完整的句子要有这两成分
追答had been doing是动词ing形式
并不等于动名词
动名词是能够单独做名词的,
这里是做动词
追问即为 had been doing是谓语动词?