IQueryable<T>的延迟执行

public PageList(IEnumerable<T> source, int index, int pageSize,int totalCount)
        {
            this.AddRange(source.Skip(index*pageSize).Take(pageSize));
            this.TotalCount = source.Count();
            this.PageSize=pageSize;
            this.PageIndex=index;

            this.TotalPageCount = (int)Math.Ceiling(TotalCount / (double)PageSize);
        }

据说使用IQueryable<T>后,source.Skip(index*pageSize).Take(pageSize)将与原来的source共同执行