多焦ERG对下列哪项的诊断更有价值( )
A．视网膜母细胞瘤B．视 * * 水肿C．老年黄斑变性D．视网膜色素变性E．青光眼
参考答案：C
— that he managed toget the information?
— Oh, a friend of his helped him. [ ]
A. Where was it
B. What was it
C. How was it
D. Why was it
当给定一个方向时，对称度的公差带形状是（）
