comboBox的dropdownstyle的属性设为DropDownList，items属性里设置几个下拉选项，如何在窗口启动时设置一个选项做为默认的填到combobox的text属性里?

private void Form1_Load(object sender, System.EventArgs e)
{
this.comboBox1.SelectedIndex = 3;
}