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- 2011-7-11
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2#
发表于 2011-7-13 16:48
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I've heard those machines are really sophisticated. They can tell when you've erased an answer, no matter how well you think you've gotten rid of it, but they recognize that it has been erased, which is the important thing. They must be able to detect which mark is stronger, and go based on that. |
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