随着时间的推移，不同的古代人类部族已经制造出各种不同类型的石质工具。
Over time, various groups of ancient humans have made various types of stone tools.
JES：你现在知道，花费一点工作量，你就能使用同样的设计方法、原材料和工具制造任何类型的摩托车。
JES: you may have then realised that, with a little extra work, you could create a whole family of bikes that were essentially similar using the same basic design and materials and tools.
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