string plate="粤BN1223";

        if (plate.Contains("粤BN"))

            {

                //除掉前三个字符，剩下的4个字符全为数字方为特殊车辆

                bool BNum = true;

                char[] strSubCCode = new char[];

                if (plate.Length == )

                {

                    plate.CopyTo(, strSubCCode, , );

                    foreach (char c in strSubCCode)

                    {

                        if (!Char.IsNumber(c))

                        {

                            BNum = false;

                            break;

                        }

                    }

                    if (BNum)

                    {

                            Print.Log("特殊车辆:" + plate+ ",免费放行");

                    }

                }

            }