— ______ apple a day keeps the doctor away!

— What do you mean? I have never heard of ______ saying before. [ ]

A. An, a

B. An, the

C. A, the

D. A, a

诊断睡眠呼吸暂停综合征的金标准是（）

A.血气分析

B.电子鼻咽镜

C.MRI

D.PSG

E.CT