can't hold a candle to sb. 不能和某人比
A: Are you falling for someone in our company?
B: Nothing of the sort, I know few people in the company.
A: But you do seem to fall for Lucy.
B: Well, I like her, but I can't hold a candle to her. I'm not her match.
carry coals to Newcastle 徒劳无益
A: Jane asked me how to solve that problem yesterday.
B: You gave her the suggestion.
B: Don't do such a thing again.
A: What's wrong?
B: You just carry coals to Newcastle. She already has her own ideas. She just pretended to ask you.