fall a prey
It's "to fall prey"Meaning: to be a victim or to be harmed by someone or somethingusage: We should not fall prey to today's advertising world.
Beware that you do not fall a prey to the highwaymen who stalk these roads.
If you are too trusting, you will fall prey to con artists and internet scams.
Ever since the funeral, Aunt Bessy was liable to fall apart at the least mention of Uncle Billy.
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.
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.
yes, it is.
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.
That IS a sentence.
"Throw the book at him" IS a sentence.