Later, in a letter to Skinner, Pressey would concede there was a massive pedagogical limitation to the device: Students learned how to master the machine, but not the subject matter.
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，这一点在safew官方版本下载中也有详细论述
比起“瞒天过海”，更让人意外的是“精确斩首”。
two x_j are the same, there exists a unique polynomial