以下哪项不是影响旅游购买行为的主要因素（）。
A.旅游者个人特点
B.社会影响因素
C.环境因素的函数
D.个人收入
参考答案：D
The man we followed suddenly stopped and looked around as if _____ whether he was going in the
right direction. [ ]
A. seeing
B. having seen
C. to see
D. to have seen
铸造3/4冠与铸造全冠比较，其优点是()
A．牙冠的边缘显露金属
B．磨除的牙体组织较少
C．边缘线长
D．必须做邻轴沟
E．固位力强
