HSK 7-9
力不从心
lìbùcóngxīn(idiom) to lack the ability to do what one would wish
他想帮忙却感到力不从心。
Tā xiǎng bāngmáng què gǎndào lìbùcóngxīn.
He wanted to help but felt unable to do as much as he wished.
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Appears across levels (7-9) in the HSK 3.0 word list.