+0
Can I say,

The patient is sitting in / on the wheelchair.
Comments  
Hi,
Use in.

Regards
why don't we use on? could you tell me the reason? Thanks!
Teachers: We supply a list of EFL job vacancies
The patient is sitting on the wheel chair.

SS
Hi,

'Sitting in' is commonly said for a chair that has arms or that is very soft.
I thin the underlying idea is that it sort of wraps around your body a bit.

Clive
So, do you accept " on the wheel chair"?
Students: We have free audio pronunciation exercises.
You could use 'on' and get away with it I think. But it is far more common for native speakers to say and use 'in' instead.
Hi,

Don''t say 'on'.

Clive