Ready for my biggest pet peeve? Lay vs. lie. Why? Because I don't think it's that hard. I mean, if I can get it, anyone can. Yes, I'm a word geek, but people much smarter than I get this wrong all the time. But let's not make this a judgment about intelligence. (After all, my money-geek friends are probably saying, "I can't believe Anne doesn't get the concept of compound interest!") Let's just try to make this easy for everyone.
I think so many people get this wrong for one of two reasons: 1) they get confused because lay, while having a different meaning from lie, is also the past tense of lie; or 2) they think lay and lie are interchangeable and it's just a matter of how you choose to pronounce it (like EE-ther vs. EYE-ther for the word either).
Whatever the reason, here's the scoop. (And while many rules of English grammar are not black and white, this one is.)
Lay means "to set" and requires a direct object. (Please lay the book on the table.)
Lie means "to recline." (I'm going to lie down for a nap.)
When you move to past tense, it gets trickier:
Yesterday, I laid the book on the table.
Yesterday, I lay down for a nap.
And you will almost never hear the correct past participle used:
For the last few days, I have laid the book on the table.
For the last few days, I have lain down for a nap.
Ever hear anyone say "lain"? Didn't think so. No matter. YOU can be the first. But, really, for the most part, if you just concentrate on mentally saying "set" or "recline" before you utter either L word, you should be OK. And your word-geek friends will love you for it.