印章

例句：

1. 1. The official stamp is used to authenticate documents.
   官方印章用于验证文件。
2. 2. The stamp on the envelope indicates that it has been opened and read.
   信封上的印章表明它已被打开并阅读过。
3. 3. The stamp collectors are busy collecting rare stamps for their collection.
   集邮者忙于收集稀有邮票以供收藏。