We use the preposition “on” when the vehicle is larger and there is space to walk around inside. The opposite preposition (off) can also be used with these means of transport.
Typical examples; train, plane, bus, boat, ferry, underground, tram, ship
Be careful you don’t trip when you get on the bus.
She is going to France on a ship.
Do we get off the plane now?
We’d like everybody to get off the train, please.
We also use this proposition when you are physically on top of the transport.
Typical examples: bicycle, motorbike, horse, scooter, tricycle
I travel to school on my bicycle.
Can you get on the horse?
Responses