Some people haven't realized something as common as _____ to the sun for a long time will do harm to their skin and even cause skin cancer.[ ]

A. exposing    

B. being exposed  

C. having exposed    

D. exposed

天南星具有的功效是（）

A.降逆止呕

B.祛风解痉

C.祛风解毒

D.止咳平喘

E.清热定惊