某些人在收入比较低时购买黑白电视机，而在收入提高时，则去购买彩色电视机，黑白电视机对这些人来说是劣质商品。
A. 对
B. 错
某消费者需求曲线上的各点是表示该消费者的效用最大的点。
A. 对
B. 错
__________ difficulties they may come across, they will help one another to get over them.
A. However
B. Whatever
C. Whichever
D. Wherever
____________ you should remain modest.
A. Whatever high your academic level is
B. However high your academic level is
C. Whichever is your high academic level
D. However your academic level is high
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