Question

1. She works as a cleaner in/at a hospital.
(Which preposition do I have to use?)

2. She spent two weeks in hospital/ in the hospital.
(Are both OK? Do you use 'in hospital' in th UK? Do you use 'in the hospital' in the USA?)

3. I had to go to hospital.
4. I had to go to the hospital.
(Are both OK? Do you use 'to hospital' in the UK? Do you use 'to the hospital' in the USA? In #4, does the hospital mean a specific hospital or is 'the hospital' in generic use?)

Answer 1

1. Either preposition works fine.

2, 3, and 4 -- "in hospital" and "to hospital" are UK expressions. Adding "the" is the normal expression in the US.

In both expressions, it's the generic use of "hospital." If someone meant a specific hospital, he/she would name it:

Generic -- She was taken to the hospital by ambulance. [but we don't know which one unless there's only one hospital in town!]

Specific -- She was taken to MD Anderson Hospital by ambulance.