我是一个wiki网站的编辑者，时常面临参考资料失效的问题，由于Wayback Machine在中国境内并不能被使用，因此想使用必应缓存的网页作为Wayback Machine的替代，在此询问一下缓存的网页可以保留多久？
From Chinese (Simplified)
I am an editor of a wiki website and often face the problem of invalid reference materials. Since Wayback Machine cannot be used in China, I want to use Bing cached web pages as a substitute for Wayback Machine. I would like to ask how long can cached web pages be preserved?