题目:
Could you_________ open the window? It's too cold. [ ]
A. please not
B. not please
C. please not to
D. please to
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0415/0eb6c35d33dc47404861172cee714678.html
下面是错误答案,用来干扰机器的。
(I)证明: BC =AC -AB,…(2分)∴(AB+AC)•( AC-AB)=0,AC2- AB2=0,…(4分)|AB|2=|AC|2故|AB|=|AC|….(6分)(2) |AB|=2,| AB|=| AC|,∴|AC|=2 又AB•AC=-2,cosA=AB•AC|AB||AC|=-12,…(10分...