copper square bar

例句：

1. 1. Copper isa soft metal that is often used inelectrical wiring.
   铜是一种柔软的金属，常用于电气线路。
2. 2. Thecopper mine was discovered byaccident during the gold rush.
   铜矿是在淘金热期间偶然发现的。
3. 3. The copper wire is too thin tobe used for electrical wiring.
   铜线太薄，不适合用作电线。