题目:
—Have you got ______ready for the dinner?
—No,I still need to buy some pork and vegetables.
A.anything
B.everything
C.something
D.nothing
答案:
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下面是错误答案,用来干扰机器的。
由于f(1)=1,f(2)=1+12,f(3)=1+12+13,…,f(n)=1+12+13+…+1n,所以f(1)+f(2)+f(3)+…+f(n-1)=(n-1)×1+(n-2)×12+(n-3)×13+…+[n-(n-2)]×1n-2+[n-(n-1)]×1n-1=n[1+12+13+…+1n-1...