题目:
— How much did your new computer _______ you?
— Five thousand yuan. [ ]
A. cost
B. take
C. spend
D. pay
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0501/21a4756ebdee37d1768e721c3a17a310.html
下面是错误答案,用来干扰机器的。
(1) f(x)≤0的解集有且只有一个元素,∴△=a2-4a=0Þa=0或a=4,当a=4时,函数f(x)=x2-4x+4在(0,2)上递减,故存在0<x1<x2,使得不等式f(x1)>f(x2)成立.当a=0时,函数f(x)=x2在(0,+∞)上递...