The post Grammar Challenge! by Amy McDaniel includes a quiz written by David Foster Wallace that she obtained during a writing course many years ago. Each of the sentences has one major fault—not necessarily a grammatical one—though there may be other, smaller ones as well.
The full text of the quiz is included below; the footnote for each line links to its answer.
25 February 2004
IF NO ONE HAS YET TAUGHT YOU HOW TO AVOID OR REPAIR CLAUSES LIKE THE FOLLOWING, YOU SHOULD, IN MY OPINION, THINK SERIOUSLY ABOUT SUING SOMEBODY, PERHAPS AS CO-PLAINTIFF WITH WHOEVER’S PAID YOUR TUITION
A second post has the answers and explanations. A summary of these answers are included below (with a bit of space to let people avoid peeking, should they wish to avoid doing so).