infinitive present past participle
to lie lie,lies lay have/has lain
to lay lay,lays laid have/has laid
To lie is to recline, or sprawl out, as in "I think I'll lie in the sun. Yesterday I lay in the sun. Have you lain in the sun?"
To lay is to set, as in "I can't find my pencil. I laid it on the table a minute ago, where I always lay it. I've laid it there every day for the past 17 years!"
To help remember: