Can you tell me your _____ of success?

There is no easy way to learn English well. Just work hard.[ ]

A. duty

B. trouble

C. secret

D. rule

款冬花的性状特征是（）

A.呈长圆棒状，外面被有多数鱼鳞状苞片，撕开后可见白色茸毛

B.为黄色粉末

C.为不带子房的管状花

D.多皱缩呈条状，完整者长9～15cm

E.呈线性，三分枝