选择设置comboBox默认值

 for (int i = 1; i <= 10; i++)
            {
string[] str = {"项目"+i};
foreach (string s in str)
                {
this.comboBox1.Items.Add(s.ToString());
                }
            }
//comboBox1.SelectedIndex = 2;
            comboBox1.SelectedIndex = comboBox1.Items.IndexOf("项目2");