I'm going to tackle, with no padding or helmet, the fearsome "Lay versus Lie". I murder this nugget of grammardom often. So here I teach myself, and if others learn, so be it!
1. The verb "to lie" is when a person reclines in the horizontalish position.
2. The verb "to lay" always involves an object that is put down. Physically, that is. We are not insulting the object!
First off, Present tense.
1. George lies on the bed.
2. George lays the book on the table. Or, I lay the book down. Here, there is always an object being put down. An easy way to remember? "The chicken lays an egg." Though the meaning is different, luckily it still works as a handy reference. It never sounds right to say, "The chicken lies an egg." There's always an object.
1. George lay on the bed. Oh crap. Here's where it gets confusing. Because past tense of "to lie" is the same word for present tense of the verb "to lay", see above. Also, it's triple confusing when you say "George lay down on the bed" Because we often follow "lay" with "down" and the slurring of the words makes it sound like "laid down". In conversation, who cares. On paper, "laid down" is wrong. Also, there is no such thing as "lied down," either, so chuck them both far, far away.
2. George laid the book on the table.
Past participle. Stay with me! Drink a cappucino if you need to!
1. George had lain on the bed for hours, unable to understand his grammar lesson.
2. George had laid the book on the table before he collapsed from a grammar stroke.
Here's a handy-dandy reference from the FreeTeach website.
I have a headache! Good luck!