LIstBox控件的一个问题

Question

listBox1.SelectedItems.Remove和listBox1.Items.Remove有什么区别？
private void button1_Click(object sender, EventArgs e)
{
if (textBox1.Text == "")
{
MessageBox.Show("当前没有输入内容", "提示");
}
else
{
listBox1.Items.Add(textBox1.Text);
textBox1.Text = "";
}
}

    private void button2_Click(object sender, EventArgs e)
    {
        if (listBox1.SelectedItems.Count == 0)
        {
            MessageBox.Show("当前没有选择内容", "提示");
        }
        else
        {
            //listBox1.SelectedItems.Remove(listBox1.SelectedItem);
            listBox1.Items.Remove(listBox1.SelectedItem);
        }
    }

Answer 1

listBox1.Items.Remove(listBox1.SelectedItems[0]);