根据购买者购买数量、购买对象、购买主体等各项因素的不同而制定不同价格的定价法叫做价格歧视。（）
查看答案
实行价格歧视所得的总收益高于实行统一定价所得的总收益。（）
A. 对
B. 错
It is necessary that theguard (monitor)the main entrance at night.
The teacher insisted that the students (be) more careful in exams.
It is high time that theboy (eat) less sugar
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