C-4：carry coals to Newcastle 徒劳无益
A:Jane asked me how to solve that problem yesterday.
A:昨天简问我怎么解决那问题。
B:You gave her the suggestion.
B:你给她建议了。
A:Yeah.
A:对呀。
B:Don't do such a thing again.
B:下次别干这种事了。
A:What's wrong?
A:怎么了？
B:You just carry coals to Newcastle. She already has her own ideas. She just pretended to ask you.
B:你做的事徒劳无益，她已经有了自己的见解。她只是问问你罢了。
