我们的证明书以盖公章有效。
The unit that delegates the authority must sign its name or affix its official seal.责任代理单位必须签上自己的名称或者粘贴官方封印。
A department manager, have lost a bag when they go out, which in addition to some money, as well as the company's official seal.有一位部门经理,有一次外出时丢失了手提包,里面除了一些钱物,还有公司的公章。