We have a high regard for Mr. Black because he always tries to ________ his principles. [ ]

A. live up to        

B. look forward to    

C. catch up with    

D. put up with

关于毛周角化病错误的是（）

A.多见于儿童及青少年

B.好发于上臂外侧

C.冬重夏轻

D.自觉症状较重

E.一般无自觉症状