One thing you should pay attention to is wether your verb is Transitive or Intransitive. Transitive would mean that your verb needs an object, just as the verb lay does. After lay you'll need an object, so you lay something on something else. While after lie you don't need an object. You lie on your back, but you can't lie something on the bed!
The past form of lie, however, is lay. So try not to mix them up.
PS: In your dictionary you'll find i for intransitive verbs, and t for transitive ones.
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