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to weaken; to grow weak; to wane; to decline (of one's health)
to be downcast; to be dejected; to be dispirited
to be troubled; to be at a loss; to be perplexed; to be annoyed
長期の闘病生活で父の体は弱ってしまった。
My father's body weakened from the long battle with illness.
急な依頼を受けて正直弱っているところだ。
I'm honestly troubled by the sudden request I received.
日照り続きで畑の野菜が弱っている。
The vegetables in the field are wilting due to the continued drought.