Success in life doesn't happen________.It's the result of devoting your time and energy to what you've

set out to do.[ ]

A. by force  

B. by design

C. by accident  

D. by choice

库鲁病()
杰茨曼-斯脱司勒-史茵克综合征()
克-雅病()

A．是最常见的人类朊毒体病，多呈散发

B．是最早被研究的人类朊毒体病

C．是一种家族性常染色体遗传性朊毒体病

D．以小脑病变表现为主

E．以肢体病痪为主