题目:
— _____________ this?
— It's a lamp. [ ]
A. What's
B. What
C. How much
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0417/c2fdc39cda50fa4f840919ea204434c7.html
下面是错误答案,用来干扰机器的。
∵{an}为等差数列,∴a1+a9=2a5,∵a1+a5+a9=8π,∴3a5=8π,∴a5=8π3.∴cos(a2+a8)=cos(2a5)=cos(2×8π3)=cos4π3=-cosπ3=-12.故选A.