private void Timer_OpSuiv_Tick(object sender, EventArgs e)
        {
            if (sec_OpSuiv < 3)
            {
                sec_OpSuiv++;
            }
            else
            {
                Timer_OpSuiv.Stop();

                Lbl_Info_Rep.Visible   = false;
                Lbl_Calcul.Visible     = true;
                Lbl_Egal.Visible       = true;
                TextB_Reponse.Visible  = true;
                Btn_Validation.Enabled = true;
            }
        }
        private void Btn_Validation_Click(object sender, EventArgs e)
        {
            Timer_Difficulte.Stop();
            sec_difficile          = 0;
            Btn_Validation.Enabled = false;

            if (Compteur_Operation < 9)
            {
                string bonne_rep = "" + Bonne_Rep;
                if (TextB_Reponse.Text == bonne_rep)
                {
                    Lbl_Info_Rep.Text = "OK";
                    nb_Bonne_Rep++;
                }
                else
                {
                    Lbl_Info_Rep.Text = "Mauvaise réponse, la bonne réponse était " + bonne_rep;
                }

                Lbl_Info_Rep.Visible = true;
                Timer_OpSuiv.Start();

                Lbl_Calcul.Text    = "";
                TextB_Reponse.Text = "";

                Lbl_Calcul.Visible    = false;
                Lbl_Egal.Visible      = false;
                TextB_Reponse.Visible = false;

                Compteur_Operation++;
                Timer_Difficulte.Start();
                Lbl_Calcul.Text = operations.tabCalcul[Compteur_Operation];
                Bonne_Rep       = operations.tabRep[Compteur_Operation];
            }
            else
            {
                string bonne_rep = "" + Bonne_Rep;
                if (TextB_Reponse.Text == bonne_rep)
                {
                    nb_Bonne_Rep++;
                }
                string fin = "L'épreuve est terminée ! \n Vous avez " + nb_Bonne_Rep * 10 + "%  de bonnes réponses";
                MessageBox.Show(fin, "fin de l'exercice", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
        }
        private void Timer_Difficulte_Tick(object sender, EventArgs e)
        {
            if (sec_difficile < 5)
            {
                sec_difficile++;
            }
            else
            {
                Timer_Difficulte.Stop();
                Lbl_Calcul.Visible     = false;
                Lbl_Egal.Visible       = false;
                TextB_Reponse.Visible  = false;
                Btn_Validation.Enabled = false;

                if (Compteur_Operation < 9)
                {
                    Lbl_Info_Rep.Text    = "Trop tard !";
                    TextB_Reponse.Text   = "";
                    Lbl_Info_Rep.Visible = true;
                    Timer_OpSuiv.Start();

                    Lbl_Calcul.Text    = "";
                    TextB_Reponse.Text = "";

                    Lbl_Calcul.Visible    = false;
                    Lbl_Egal.Visible      = false;
                    TextB_Reponse.Visible = false;

                    Compteur_Operation++;
                    Lbl_Calcul.Text = operations.tabCalcul[Compteur_Operation];
                    Bonne_Rep       = operations.tabRep[Compteur_Operation];
                    sec_difficile   = 0;
                    Timer_Difficulte.Start();
                }
                else
                {
                    string fin = "L'épreuve est terminée ! \n Vous avez " + nb_Bonne_Rep * 10 + "%  de bonnes réponses";
                    MessageBox.Show(fin, "fin de l'exercice", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
                sec_difficile = 0;
            }
        }