白描的作用是（）
A.绘画作品创作的草稿
B.绘画的保存和传播
C.徒弟学画的方式
D.以上都是
参考答案：D
骨折专有体征是：（）
A．畸形
B．反常活动
C．骨擦音
D．畸形、反常活动、骨擦音
The young tennis player has often _____ famous players, but so far he has always been beaten.[ ]
A. competed for
B. competed over
C. competed with
D. competed in
