Mrs. Black doesn't believe that her son is able to design a digital camera, ______?[ ]

A. is he  

B. isn't he    

C. doesn't she    

D. does she

邱学华的“尝试教学法”强调在教师的指导时，应充分发挥哪些作用（）。

A.旧知识的基础作用

B.准备题的引导作用

C.课本的示范作用

D.学生之间的互补作用