It's very warm. You           wear the coat.          [ ]

A. must                      

B. don't have to

C. have to                    

D. mustn't

黄连能透过血脑屏障而产生中枢抑制作用的成分是（）

A.小檗碱

B.黄连碱

C.四氢黄连碱

D.药根碱

E.甲基黄连碱