Up the creek without a paddle: phrase or dependent clause?

If I had my 28-hour day today, there's no doubt in my mind that I'd spend the extra four hours studying for the grammar test I'm taking tomorrow. But four hours wouldn't even cut it. Four months and four hours would probably suffice.

You'd think that because I speak English, I would have English grammar nailed, but no.  My head is swimming with exceptions to the rules. Every time I think I've got it, a preposition in disguise jumps out and ruins everything.

But enough with the procrastination. I'm going to go uncross my eyes and get back to the books.