Someone or something that is in something else is enclosed by it or surrounded by it. If you put something in a container, you move it so that it is enclosed by the container.
He was in his car.
...clothes hanging in the wardrobe...
If something happens in a place, it happens there.
We spent a few days in a hotel...
He had intended to take a holiday in America...
If you are in, you are present at your home or place of work.
My flatmate was in at the time...
He has had to be in every day.
When someone comes in, they enter a room or building.
She looked up anxiously as he came in...
They shook hands and went in.
If a train, boat, or plane has come in or is in, it has arrived at a station, port, or airport.
We'd be watching every plane coming in from Melbourne...
Look. The train's in. We'll have to run for it now.
When the sea or tide comes in, the sea moves towards the shore rather than away from it.
She thought of the tide rushing in, covering the wet sand...
If the tide was in they went swimming.
Something that is in a window, especially a shop window, is just behind the window so that you can see it from outside.
The light in the window went out...
There was a camera for sale in the window.
When you see something in a mirror, the mirror shows an image of it.
I couldn't bear to see my reflection in the mirror...
He caught sight of his hair in a mirror.
If you are dressed in a piece of clothing, you are wearing it.
He was a big man, smartly dressed in a suit and tie.
...three women in black.
Something that is covered or wrapped in something else has that thing over or round its surface.
His legs were covered in mud.
...carrots wrapped in newspaper.
If there is something such as a crack or hole in something, there is a crack or hole on its surface.
There was a deep crack in the ceiling above him.
...an unsightly hole in the garden.