旅游道德是把一般______与______结合起来的职业行为规范或标准。
参考答案：社会道德职业特点
We are having a party and everyone ________ a good time.[ ]
A. having
B. have
C. is having
D. are having
图示体系是几何（）的体系。
A．不变
B．不变且无多余约束
C．瞬变
D．不变，有一个多余约束
