I saw this little quiz on Don't MAKE Me Get My Flying Monkees. What the heck! It's something to post on a Saturday. Almost all you have to know to ace this sucker is there, they're, their, it's and its.
Your Language Arts Grade: 100%
Way to go! You know not to trust the MS Grammar Check and you know "no" from "know." Now, go forth and spread the good word (or at least, the proper use of apostrophes).