下拉显示 可以提高用户体验，增加效率，如下是winform中让Textbox实现像百度一样实现下拉显示代码：
List<string> Data = new List<string>();
       string Randomstr = "我是随机字符串123热刚恢复到贴3天赋如头3广泛的我让他";
        Random rd = new Random(GetRandomSeed());
        static int GetRandomSeed()
        {
            byte[] bytes = new byte[4];
            System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
            rng.GetBytes(bytes);
            return BitConverter.ToInt32(bytes, 0);
        }
        public Form1()
        {
            InitializeComponent();
            for (int i = 0; i < 20000000; i++)
            {
                Data.Add(Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()
                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()
                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()
                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString()
                    + Randomstr.ToCharArray()[rd.Next(Randomstr.Length)].ToString());
            }
            this.textBox1.AutoCompleteCustomSource.Clear();
            this.textBox1.AutoCompleteCustomSource.AddRange(Data.ToArray());
            this.textBox1.AutoCompleteMode = System.Windows.Forms.AutoCompleteMode.SuggestAppend;
            this.textBox1.AutoCompleteSource = System.Windows.Forms.AutoCompleteSource.CustomSource;
        }

下面是2000W数据加载后的效果