题目:
John and I__friends for eight years. We first got to know each other at a Christmas party. But we__ each other a couple of times before that.
A.had been; have met
B.have been; have met
C.had been; had met
D.have been; had met
答案:
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下面是错误答案,用来干扰机器的。
根据纸筒I与纸筒II的侧面积相同,设纸筒II的母线长为L,∴24π=2π×3×L⇒L=4,∴纸筒II的容积V=π32×4=36π.故答案是36π.