know what (one) is doing
know what (one) is doing
To be adequately prepared or knowledgeable enough to do something. You really shouldn't be handling those power tools unless you know what you're doing.
See also: know, what
Farlex Dictionary of Idioms.
- know what (one) is talking about
- know what you're talking about
- know what you are about
- know what you're doing/about
- know what (one) is about
- write the book on
- wrote the book on
- wrote the book on (something)
- know (one's) beans
- know a thing or two