First, the BHO is tied to the browser's main window.

首先，BHO对象依托于浏览器主窗口。

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Any instance of the BHO lives and dies with the browser's instance.

任何BHO对象与浏览器实例的生命周期是一致的。

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The only strict requirement for a BHO is implementing this interface.

对BHO的唯一严格的要求正在于必须实现这一个接口。

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"The initial program installed itself as a browser helper object (BHO) for Internet Explorer that downloaded a component from childhe.com and attempted to trick the victim into installing a fake anti-virus scanner from bestantispyware securityscan.com and protectionsoft warecheck.com, " he explained.

BBC: Hackers website