"To be in" means that the person is home -- it's a short version of saying "to be in the house"
An idiom usually is a sentence, or part of one. It certainly can be used as part of a sentence. The way to tell if it's an idiom is if it makes sense the way it's literally written.
The idiom is "when pigs fly". Bacon comes from pigs, but bacon is not in the idiom. The idiom simply means, "impossible".
Nothing. You have left out part of the idiom. Perhaps you mean "your hands are tied," which means that you have no power to do anything in a given situation.
the sultry part of the summer
You cannot understand an idiom without knowing ahead of time what it means. A phrase is just part of a normal sentence.
it means an idiom/per
It means find that part in the heart, tell what it has, and what it is.
Its the big part f something
Hurry up, finish what you started, whats the main part of this question, stuff like that. It's not necessarily and idiom, just a popular saying people use.
This is a sports idiom. If you're not playing well enough, the coach makes you sit on the sidelines of the field instead of joining the game. If you are sitting on the sidelines, you are not participating. You have been "benched." The idiom means that you're not part of whatever is going on.
Idiom is correct.
Start from scratch is an idiom it is not a part of speech. It contains a verb -start, a preposition - from and a noun - scratch