题目内容：
回答(47)题 A．Andothershavepainfulattacksallthetime.
B．Thesesignalstravelfromnervecellsintheinjuredarea,upthespinalcord(脊髓)tothebrain,andbackdownagain.
C．Ittellsusthatweareinjuredandshoulddosomethingaboutit.
D．Theyknewlittleabouttheprocessofpainitself.
E．Theothermessagemovesataspeedofonly30metersasecond.
F．Andtheysendthesecond,slowermessageofpaintothebrain.
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答案解析：