关于视网膜中央动脉阻塞的叙述，正确的是
A．动脉管径无变化
B．动脉变细，静脉变粗
C．动脉变细，静脉变细
D．静脉管径无变化
E．以上都不对
参考答案：C
The old man came to our restaurant so ____ that all of us were familiar with him. [ ]
A. frequently
B. gradually
C. fluently
D. equally
国际技术经营有哪些形式？
