by StaceyKoprince Tue Jun 02, 2009 3:31 pm
The tricky part here is that "life as we know it (life)" is a common idiomatic expression. Idiomatic expressions don't necessarily follow all of the nitty-gritty rules of grammar. This is one of those things that is "just the way we say it."
Also, the prepositional phrase thing you're referring to - it is not the case that a pronoun can never refer to a noun in a prepositional phrase. It's more complicated than that. If you have a prepositional phrase that modifies a separate clause, then a pronoun in that separate clause cannot refer to the noun in the prepositional phrase.
With an egg in his hand, Harold broke it.
The opening part is a prepositional phrase and that prep phrase modifies the clause after the comma, Harold broke it. The pronoun in that separate clause cannot modify the word "egg" in the prepositional phrase because the prepositional phrase itself is already a modifier of the "Harold broke it" clause - it's like a big modifying loop.
in this case, "life as we know it" is one complete clause - "of biochem-based life" is not a prepositional phrase modifying the separate clause "as we know it."
Stacey Koprince
Instructor
Director, Content & Curriculum
ManhattanPrep