Answers and explanations for the 2007 Multiple-Choice segment

By opening this link, you should see a document with all the answers -- plus brief, student-written explanations -- to last week's AP Multiple Choice test.  The student writing needs some drastic proofreading, especially for punctuation, but the underlying thinking is pretty strong.

(The percentages indicate the number of students on the nation-wide exam in 2007 who got the right answer.  Thus, a 40% answer, like the answer to #1, was difficult for most students, whereas an 80% answer, like the answer to #4, was relatively easy for most students.)

FOR MONDAY'S CLASS, please mark all the correct answers on your question sheet and look up the explanations for the ones you got wrong.