Catch on and Give the once over

Catch on verb - Understand, usually after some initial difficulty.

Give the once over and catch on are semantically related. In some cases you can use "Give the once over" instead a verb "Catch on".

Give the once over verb - Look at with a critical eye.

Catch on and give the once over are semantically related. Sometimes you can use "Catch on" instead a verb "Give the once over".