sit somebody down in something
sit somebody down on something

She sat down on the ground and held up a hand.

She sat down on the bed and thought for a moment.

She sat down on the other side of the room.

She sat down on the floor in front of her.

She sat down on the bed and took them first.

He sat down on the floor, and a couple more came to him.

They both sat down on the ground, and looked at one another.

So we sat down on the ground and told him the story.

After a time, he sat down on the floor and did not move.

Then she sat down on the other end, without looking at me.