细晶强化
参考答案：
金属的晶粒愈细小，其强度、硬度愈高，这种现象称为细晶强化。
根呈圆柱形，略扁，表面有扭曲的纵纹，断面皮部呈墨绿色或棕色的中药材是（）
A.胡黄连
B.巴戟天
C.茜草
D.续断
E.玄参
Her brother is very busy with his work now, so he has _____ time to read newspaper. [ ]
A. much
B. little
C. full
D. a lot of
