Although copper and stone tools continued to be used, bronze was far more successful in creating sharp edges that could be used as anything from saws and scythes to weapons.
尽管青铜器和石器还在继续被使用，但青铜在用于制造带有锋利边缘的物件方面要成功得多，这可以应用于从锯子、镰刀到武器等任何东西。
March silver futures in the U.S. neared 30-year highs on Wednesday, and March palladium futures hit a 9-year high, while copper and gold also continued to record levels seen Tuesday.
周三在纽约商业交易所，2011年3月份交割的白银期货价格接近20年来新高，3月份交割的钯金价格创下9年来新高，铜和黄金价格也持续升至历史高位。
The reason for the continued use of analog video includes easy access to low cost circuit designs, use of inexpensive copper cabling, and analog video degrades "gracefully" in noisy environments.
继续使用模拟视频的原因包括：很容易获得低成本电路设计、可以使用低廉的铜线缆，以及在嘈杂的环境中模拟视频性能的下降比较平缓。
The reason for the continued use of analog video includes easy access to low cost circuit designs, use of inexpensive copper cabling, and analog video degrades "gracefully" in noisy environments.
继续使用模拟视频的原因包括：很容易获得低成本电路设计、可以使用低廉的铜线缆，以及在嘈杂的环境中模拟视频性能的下降比较平缓。
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