this.comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
            this.comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;

------解决方案--------------------
this.comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
           this.comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;


------解决方案--------------------
C# code
private void comboBox1_TextChanged(object sender, EventArgs e)
        {
            string str = this.comboBox1.Text;
            for (int i = 0; i < this.comboBox1.Items.Count; i++)
            {
                if (this.comboBox1.Items[i].ToString().IndexOf(str) == 0)
                {
                    this.comboBox1.Text = this.comboBox1.Items[i].ToString();
                    this.comboBox1.Select(str.Length, this.comboBox1.Text.Length - str.Length);
                    break;
                }
            }
        }

------解决方案--------------------
探讨

C# code
            this.comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
            this.comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;


------解决方案--------------------
探讨

C# code
            this.comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
            this.comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;


------解决方案--------------------

探讨

C# code
            this.comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
            this.comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;