Everybody present at the meeting agreed to stick to the ________ that everyone should be treated fairly.[       ]

A. purpose  

B. ambition

C. principle  

D. level

下列药物炮制后质变酥脆，易于粉碎及煎出有效成分，并能矫臭矫味的是

A．僵蚕

B．槐花

C．鳖甲

D．磁石

E．龙骨