He’s so ill that his father has to send for doctor.A. oneB. someC. aD. the

问题补充：

He’s so ill that his father has to send for doctor.

A. one

B. some

C. a

D. the

答案：

A. one

B. some

(答案→)C. a

D. the

解析：这里用a表示泛指。