如何查看CACHE。ADD 后的到期时间？高手来！~

Question

object o = new object();            HttpContext.Current.Cache.Insert(
               "aaa",
                o,
                null,
                DateTime.Now.AddSeconds(18000),  
                System.Web.Caching.Cache.NoSlidingExpiration, System.Web.Caching.CacheItemPriority.NotRemovable, null);
        我想遍列 查看 cache 列表 及时间。如何做？我观察发现 aaa 老是 提前被清除掉。想找到原因并解决！