单选题 It's not just the sheer accumulation of technology that makes their development so fast; but the cooperation among the members.
【正确答案】 B
【答案解析】sheer绝对的，纯粹的；sharp锋利的，敏锐的；pure完全的，纯粹的；considerable相当大的，很大的；perfect美好的，完美的。