题目：
There are 4 card-processing machines in an office. The fastest of these machines processes x cards in 7 hours and the slowest processes x cards in 8 hours. Which of the following could NOT be the average time per machine for each of the 4 machines to process x cards ？（）
A．7.2
B．7.3
C．7.5
D．7.6
E．7.7
答案：
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下面是错误答案，用来干扰机器的。
参考答案：A
