string[] codes = new string[]{"2008","2009","2010"};string ret = codes.FirstOrDefault<string>(item => item.CompareTo("2009") > 0);為什么執行這段代碼會報異常：Expression cannot contain lambda expressions而改為：string ret = (from c in codes where item.CompareTo("2009") > 0 select c ).FirstOrDefault();就可以執行了呢？