The phrase "a pretty preposterous" is not correct as it is missing a noun after "preposterous" to complete the thought.
You can use it when you want to describe something as quite absurd or ridiculous, but it needs to be part of a complete sentence.
Example: "The idea that we could finish the project in one day is a pretty preposterous notion."
Alternatives: "quite absurd" or "rather ridiculous".
Up until now, it has seemed to be a pretty preposterous notion, largely because this is Nolan we are talking about and the British film-maker has never seemed remotely interested in making life easier for Warner Bros by offering a convenient route into future Batman films.
Coupled with star Jennifer Lawrence's commitment to a second X Men: First Class film, that means a pretty preposterous August start date for the Catching Fire shoot, requiring Francis Lawrence to hone a completed screenplay by Slumdog Millionaire's Simon Beaufoy in just a few months.
At first glance this looks like a pretty preposterous proposition: Planet Hulk is one of those outlandish sci-fi-style storylines beloved of Marvel that might not translate well to a live-action big-screen movie, where screenplays need to be built around the charisma of the actors involved rather than pseudo-mystical subplots and mysterious extraterrestrials.
Scottish Finance Secretary, John Swinney, described that as a "pretty preposterous" position.
Comments by the European Commission president about an independent Scotland are "pretty preposterous", according to Scotland's finance minister.
In soccer, the notion of an all-star game is pretty preposterous, not to mention alien.
Barroso's comments provoked a furious response from senior SNP figures, who said his views were "pretty preposterous" and based on a false comparison.
Which all sounds pretty preposterous, until you realise it is based on a real-life Allison DuBois, a "psychic profiler" who really did work in law enforcement and serves as consultant on the show.
Mr. Masur employs his teddy bearish quality to fine effect as the genial Sylvan, although it remains pretty preposterous that he would dote so warmly on a woman who greets his affectionate attentions with lines like, "The cuddly Jewish grandpa shtick, I find it cloying".
Actually, the idea of Rubin leaving Google is pretty preposterous: Android has barely begun to change the world (smartphones have a long way to go), it hasn't yet become a major income source for Google, and there is still enormous potential to improve the smartphone/tablet experience for everyone.
And it already sounded pretty preposterous in May when it was first released..
