lay, lie

lie (lying), lay, lain:

            Intransitive verb meaning to recline, takes no object:

                        The hat is lying on the floor.

                        It lay there all day.

                        It has lain there for a week now.

lay (laying), laid, laid:

            Transitive verb, takes an object:

                        Lay the hat on the chair.

                        He laid it down quickly.

                        He had laid it there before.

                        It had been laid down quickly.

Note: When lay is used in the passive voice, there is no object.

Idiomatic: The hen is laying.

The nautical use of lay (lay at anchor and when meaning "to go," lay forward or aloft), though intransitive, is idiomatic.

To lay low, meaning "to bring down," should not be confused with to lie low, meaning to "stay in hiding."