稀释哮喘持续状态患者痰液的首要方法是（）

A.应用祛痰剂

B.大剂量抗生素

C.体位引流

D.应用支气管扩张剂

E.补液纠正失水

You are getting closer to the vessel（）,which is on the same course as you.

A.head

B.ahead

C.headed

D.heading