Lay and lie are both irregular verbs. If you memorize their forms, then you’ll avoid making common errors.
- The chicken lays eggs.
- I lie on the sofa.
- The chicken laid eggs yesterday.
- I lay on the sofa yesterday.
- The chicken is laying eggs right now.
- I am lying on the sofa right now.
- The chicken has laid eggs.
- I have lain on the sofa.