The old man was ill in ( ) hospital.A.a B.an C.the D./

The old man was ill in ( ) hospital.A.a B.an C.the D./

in hospital,住院

The old man was ill in hospital

The old man was ill in hospital
老人生病住院了，不用冠词，表示抽象的意思，
如The old man was ill in bed. 老人病了，卧床不起.

应该选D.