判断linq语句结果是否为空的方法

如：

var TasComID = (from ee in LinkToSQL.TasCom
                                where ee.TasComNum == cbb_TasComNum.SelectedItem.ToString() && ee.IsDeleted == false
                                select ee.TasComID).Distinct();

if(TasComID.FirstOrDefault()!=null)
                    ID = TasComID.Single();