set / sit
Set (put something down) vs. sit (take a seat), and the past tense set vs. sat.
Set takes an object: set the crate on the dock. Sit does not: Sit on the bench. The past of set is set. The past of sit is sat. Do not use sit the crate or set down when you mean sit down.
Examples
UseSet the box by the door.
UseSit by the door.
AvoidSit the box by the door.