fall down on something

Từ điển tiếng Anh - Cambridge Advanced Learners Dictionary

fall down on sth phrasal verb [ fell down on sth fallen down on sth fallen down on sth falls down on sth falling down on sth ]
to not be good at something in comparison with another thing
• I'm quite good at speaking Chinese, but I fall down on the written work.
Thesaurus⁺: ↑Failing and doing badly
Main entry: fall_{phrasal verb}