电动吸痰法最主要的目的是

A．促进呼吸道纤毛运动

B．促进IgG 分泌

C．保持呼吸道清洁

D．保持呼吸道湿润

E．保持呼吸道通畅

_______? It's 20 centigrade, it very warm today.[ ]

A. How is it    

B. What's the weather like    

C. What's it

D. How is the weather like