Как я могу исправить этот код, у меня есть только 13 ошибок, но все они CS0029. Я использую C# windows forms.net каркас

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//read and convert first operand 
            operand1 = Convert.ToDouble(operand1TextBox.Text);
            //read and convert second operand
            operand2 = Convert.ToDouble(operand2TextBox.Text);
            //compute result
            answer = operand1 + operand2;
            //format result as string and display on form
            answerTextBox.Text = String.Format("{0:N3}", answer);
        }

        private void subtractButton_Click(object sender, EventArgs e)
        {
            //read and convert first operand 
            operand1 = Convert.ToDouble(operand1TextBox.Text);
            //read and convert second operand
            operand2 = Convert.ToDouble(operand2TextBox.Text);
            //compute result
            answer = operand1 - operand2;
            //format result as string and display on form
            answerTextBox.Text = String.Format("{0:N3}", answer);
        }

        private void multiplyButton_Click(object sender, EventArgs e)
        {
            //read and convert first operand 
            operand1 = Convert.ToDouble(operand1TextBox.Text);
            //read and convert second operand
            operand2 = Convert.ToDouble(operand2TextBox.Text);
            //compute result
            answer = operand1 * operand2;
            //format result as string and display on form
            answerTextBox.Text = String.Format("{0:N3}", answer);
        }

        private void divideButton_Click(object sender, EventArgs e)
        {

            //read and convert first operand 
            operand1 = Convert.ToDouble(operand1TextBox.Text);
            //read and convert second operand
            operand2 = Convert.ToDouble(operand2TextBox.Text);
            //compute result
            if (operand2 != 0)
            {
                answer = operand1 / operand2;
                //format result as string and display on form
                answerTextBox.Text = String.Format("{0:N3}", answer);
            }
            else
            {
                //display the error
                MessageBox.Show("Cannot divide by zero. Re-enter the denominator.", "Error in denominator", MessageBoxButtons.OK, MessageBoxIcon.Error);
                //set focus back to the textbox with the data entry error
                operand2TextBox.Focus();
                operand2TextBox.SelectAll();
            }
        }

        private void clearButton_Click(object sender, EventArgs e)
        {
            //Clear text Boxes
            operand1TextBox.Clear();
            operand2TextBox.Clear();
            answerTextBox.Clear();
            //reset the focus to the top TextBox
            operand1TextBox.Focus();
        }

        private void exitButton_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}

Что я уже пробовал:

Честно говоря, я не знаю, что делать.

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