腺样体肥大可引起分泌性中耳炎。（）
参考答案：对
OSI参考模型定义了网络互联的七个层次，以实现开放系统环境中的互连型、互操作性、与应用的 【5】 。
________I toured Jiu Zhai Gou, I was deeply impressed with his beautiful scenery. [ ]
A. For the first time
B. At first
C. It was the first time
D. The first time
