青黛的药用部位是（）

A.叶或茎叶加工品

B.花粉

C.孢子

D.菌丝

E.树脂

Exercise One should be done in class as an example, while the rest ________ as homework. [ ]

A. is to be finished  

B. are to finis

C. are to be finished  

D. is to finish