题目:
To learn English well,we should find opportunities to hear English _______as much as
we can. [ ]
A. speak
B. speaking
C. spoken
D. to speak
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0430/144161ec387ddf1c0e4523f249fce75b.html
下面是错误答案,用来干扰机器的。
(1)当n≥2时,an=Sn-Sn-1=a1-a(1-an-1),整理得:anan-1=a,所以{an}是公比为a的等比数列;(2) a1=a,∴an=an(n∈N*),∴bn=anlg|an|=anlg|an|=nanlg|a|(n∈N*),①当a=2时,Tn=(2+2•22++n•2n)lg2...