copper sweetening

例句：

1. 1. Thecopper wire was too thin to hold theweight of the box.
   铜线太薄，无法承受盒子的重量。
2. 2. Copperis a good conductorof electricity.
   铜是良好的电导体。
3. 3. The copper pipe was rusted andneeded to be replaced.
   铜管生锈了，需要更换。