int i = 0;
        DateTime btime = DateTime.Now, etime = DateTime.Now;
        TimeSpan temp;
        private void timer1_Tick(object sender, EventArgs e)
        {
            if (i <= 100)
            {
                progressBar1.Value = i;
                etime = DateTime.Now;
                temp = etime.Subtract(btime);

                label1.Text = temp.Seconds + "秒";
            }
            else
                timer1.Enabled = false;

            i += 1;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            timer1.Enabled = true;
            btime = DateTime.Now;
        }