door knocker

例句：

1. 1.The door knocker on the door was a bell.
   门上的敲门器是一个铃铛。
2. 2.The old man knocked at the door and asked for the owner's name.
   那位老人敲了敲门并问主人的名字。
3. 3.The door knocker is made of brass and has a weight of about 5 pounds.
   这个门牌号是用黄铜制成的，重约5磅。