have a good command of something
idiomPart ofcommand
have a good command of something — idiom
1. to know a lot about a subject or be very skilled at using something, such as a l
1.idiom
Definition
to know a lot about a subject or be very skilled at using something, such as a language or instrument
Example
To get the job, you need to have a good command of written and spoken English.
Diego has a very good command of the violin for someone who has only been playing for three years.