—     _do you study for your math test?  

—By working with my classmates or asking the teacher for help.      [ ]

A. How                  

B. What        

C. When                  

D. Why

引起慢性肾功能不全的最常见的继发性肾脏疾病是（）

A.乙肝相关性肾炎

B.淀粉样变肾病

C.糖尿病肾病

D.良性肾小动脉硬化

E.系统性红斑狼疮