--- He has never traveled to a foreign country,        ?

--- Yes. He has been to England once.

A．does he

B．doesn't he

C．has he

D．hasn't he

雾化吸入普米克令舒的患者和口服强的松龙患者的血清骨钙素浓度比较，何种药物会降低其浓度（）。

A.雾化吸入普米克令舒

B.口服强的松龙

C.二种药物相同

D.二种药物都不会降低骨钙素浓度