Just at that time, the emperor was ill and he became very weak.

就在那时，皇帝病了，变得非常虚弱。

youdao

He became very weak towards the end of his life.

他临终时很虚弱。

《牛津词典》

Years went by, and the giant became very old and weak. He sat in his armchair and watched the children play in the garden.

很多年过去了，巨人变得年老衰弱了。他坐在自己的摇椅里看着孩子们在花园里玩。

youdao

He became weak,and his heart burst.

VOA: special.2009.02.21

At age 3 he stopped growing and became too weak to walk.

FORBES: The Ultimate Targeted Therapy

But the FDP, like the Lib Dems in England, which became his adopted country in 1988, was small and weak, and not quite what he wanted.

ECONOMIST: Ralf Dahrendorf