weak名词形式为weakness
例句如下，请你仔细体会和理解吧
1.
He became very weak towards the end of his life.
他临终时很虚弱。
2.
He was a weak little mouse of a man.
他是个懦弱无能的人。
3.
I was always weak in the science subjects.
我总是学不好理科。
