"To be" is not an idiom - it's a verb.
Pest is not an idiom. It's a word.
The idiom "apple shiner" means the teacher's pet.
The meaning of the idiom in the pink of health means being in good health.
It's not an idiom - to cope means to deal with, or to handle
The idiom means impress someone is egg on
"Old hand" is an idiom meaning having lots of experience.
It is not an idiom. It is an expression. The difference is that an idiom's meaning cannot be derived from the meaning of its individual words. In the expression wolfing down food, the meaning is clearly derived from the meaning of the words, and people have been saying it for hundreds of years.
No. This is not an idiom. An idiom is a group of words whose meaning is different from the meanings of the individual words. So it is not easy to know the meaning of an idiom. For example 'Let the cat out of the bag' is an idiom meaning to tell a secret by mistake. The meaning has nothing to do with cats or bags. "Treat others like you would want them to treat you" is a saying,
Teasing you .
Unanimously
By accident is not an idiom. It translates literally and conveys the same meaning. It means "not intentionally", "not planned", "as a result of happenstance".