Linq自定义或(or)的实现记录下来以后用到的时候从这里查

Expressionbool>> where = PredicateExtensionses.True();

Expressionbool>> orFilter = PredicateExtensionses.False();

                    foreach (string dept in lstDept)
                    {
                        string strDept = "\\" + dept + "\\";
                        orFilter = orFilter.Or(c => c.OwnUserFullPath.Contains(strDept));
                    }

where = where.And(orFilter);