世界小史 第17章:制造工具
英语课
In the end, perhaps 6,000 years ago, that is, 4,000 BC, they found a new and more convenient way of making tools: they discovered metals.
最后，约6000年以前，即公元前4000年，他们获得了一种新的更方便的制造工具的方法：他们发现了金属。
Not all of them at once, of course.
当然不是一下子同时发现了所有的金属。
It began with some green stones which turn into copper 1 when melted in a fire.
首先是那些绿色的石头，人们用火熔化它们，它们就变成了铜。
Copper has a nice shine, and you can use it to make arrowheads and axes, but it is soft and gets blunt 2 more quickly than stone.
铜闪着美丽的光，你可以用铜锻造箭头和斧子，但是铜很软，它比石头更容易变钝。
But once again, people found an answer.
人们再一次发现了解决方法。
They discovered that if you add just a little of another, very rare, metal, it makes the copper stronger.
他们发现：如果你把另一种很罕见的金属掺和进去，便能使铜变硬。
That metal is tin, and a mixture of tin and copper is called bronze.
这种金属就是锡，而铜和锡的混合物就叫做青铜。
The age in which people made themselves helmets and swords, axes and cauldrons, and bracelets 3 and necklaces out of bronze is, naturally, known as the Bronze Age.
人类用青铜制造他们的头盔、剑、斧头和锅，还有青桐制作的手镯和项链，
n.铜；铜币；铜器；adj.铜(制)的；(紫)铜色的
- The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
- Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。
adj.（刀子）钝的，不锋利的，迟钝的，直率的
- The axe is too blunt to cut down the tree.斧头太钝，砍不倒树。
- She is rather blunt in speech.她说话很直率。