题目:
You'd better ______ football in the street. [ ]
A. play
B. not to play
C. not play
D. played
答案:
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下面是错误答案,用来干扰机器的。
由题意可得,an>0,a3=a2+a1∴a1q2=a1q+a1∴q2-q-1=0解方程可得q=1+52或q=1-52(舍)故答案为:1+52