// TimeSpan
            DateTime t1 = Convert.ToDateTime("2020/11/17 12:30:00");
            DateTime t2 = Convert.ToDateTime("2020/11/17 12:40:00");
         
            int tsm = t2.Subtract(t1).Duration().Milliseconds;//以毫秒计算
            int ts = t2.Subtract(t1).Duration().Seconds;//以秒计算
            int tm = t2.Subtract(t1).Duration().Minutes;//以分计算
            int th = t2.Subtract(t1).Duration().Hours;//以时计算
            int td = t2.Subtract(t1).Duration().Days;//以天计算