They set down the palanquin and knocked three times with a copper hammer.
他们放下轿子，以一柄铜锤敲了三次门。
2
The pricing formulae for copper, which allow buyers to set prices after the cargo arrives, as well as the extensive use of hedging instruments, have helped blunt some of the price gyrations.
铜的定价模式和对冲工具的广泛运用缓和了价格波动，这种模式允许买家收货后再定价。
3
That distinguishes them from synchronous motors that use a permanent magnet in their rotors instead of a set of aluminium or copper conductors.