know your stuff
US /noʊ jʊər stʌf/
UK /noʊ jʊər stʌf/
1.
很懂行, 精通
to be very knowledgeable and skilled in a particular area or subject
:
•
You can trust her advice; she really knows her stuff when it comes to financial planning.
你可以相信她的建議；在財務規劃方面，她確實很懂行。
•
The new mechanic clearly knows his stuff; he fixed the engine in no time.
這位新機械師顯然很懂行；他很快就修好了發動機。