由于客观原因需要变更计划和日程时，导游人员要认真分析形势，对问题的______、严重性和______作出正确判断。
参考答案：性质 后果
—You _____ a meal this evening. I had dinner at a restaurant with Tom.
—Well, why didn’t you phone me and let me know?
A．should not cook
B．don’t need to cook
C．needn’t have cooked
D．should have cooked
一般油品脏污介质，常用（）*3的中低压无缝钢管。
