Task: Translation
Input (Chinese): 它最初是在维基百科页面的一个大型子集上进行测试的。维基百科是一个免费的在线百科全书项目，它会保留对每一篇文章所做的每一项更改。
Output (English): It was initially tested out on a large subset of the pages of Wikipedia, a free online encyclopedia project which preserves every change made to each of its articles.