My sister is badly ill .She is ________hospital

正确答案是A
我给区别一下in hospital和in the hospital.
in hospital是指一个病人生病在医院里,My sister is badly ill,符合这种情况.
而in the hospital,就是指一个人在医院里,一般指没有生病的,如果有人在医院陪病人,这个人就是in the hospital.