he had a painful cut on his thumb.这句话里用了哪些语法知识?

题目

he had a painful cut on his thumb.这句话里用了哪些语法知识?
“a”不是放在名词前表示数量“1”的吗?可painful是形容词啊.难道“painful”“cut”是连在一起的?
“painful cut”?痛苦的消减?
可书上写的整句话意思是“他大拇指上有伤口,很疼.”对不到的啊.

答案

he had a painful cut on his thumb.
这里的cut是名词：切口,可以加冠词,不是动词.a paintful cut,很疼的伤口.
书上写的没错.
又如：
His cheek was badly scarred by a knife cut.
他的面颊上留有严重的刀疤.