This is not an idiom. It means just what it seems to mean. It's a proverb.
And it's also a sentence already.
That nightclub used to be great , but it ` s reallygone to the dogs .
My Favorite IDIOM Is, When Pigs Fly.
Idiom
To include an idiom in an example sentence, simply incorporate the idiom naturally into the sentence to convey a figurative meaning. For example, "She had a chip on her shoulder" is an idiom meaning she was easily offended or held a grudge.
You really have a chip on your shoulder. Don't get a chip on your shoulder over such a little thing.
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 sentence is not, because an idiom is usually a phrase. The idiom is "do lunch," which means to have lunch together, usually while discussing business.
This is not an idiom. Idioms make little or no sense unless you know the definition. This sentence makes perfect sense, so it is not an idiom. The dead fish smelled so bad that even as high as Heaven, you could smell them.
That IS a sentence.
"Throw the book at him" IS a sentence.
yes
"Hit the books" is a sentence.