c# – 如何将IEnumerable>转换为List？

private void generateKeywords_Click(object sender,RoutedEventArgs e)
{
   string srText = new TextRange(
     txthtmlsource.Document.ContentStart,txthtmlsource.Document.ContentEnd).Text;
   List<string> lstShuffle = srText.Split(' ')
       .Select(p => p.ToString().Trim().Replace("rn",""))
       .ToList<string>();
   lstShuffle = GetPermutations(lstShuffle)
       .Select(pr => pr.ToString())
       .ToList();
}

public static IEnumerable<IEnumerable<T>> GetPermutations<T>(
                                              IEnumerable<T> items)
{
    if (items.Count() > 1)
    {
        return items
          .SelectMany(
             item => GetPermutations(items.Where(i => !i.Equals(item))),(item,permutation) => new[] { item }.Concat(permutation));
    }
    else
    {
        return new[] { items };
    }
}

下面这一行失败,因为我无法正常转换.我的意思是不是错误,但也不是字符串列表

lstShuffle = GetPermutations(lstShuffle).Select(pr => pr.ToString()).ToList();