asp.net c# 删除弹出提示框

<mce:script type="text/javascript"><!-- function Delete() { var grade = document.getElementById('<%=txtGrade.ClientID %>'); return confirm("要删除"+grade.value+"级的学生吗？"); } // --></mce:script> <asp:Button ID="btnDelete" runat="server" Text="删除数据" οnclick="btnDelete_Click" OnClientClick="Delete()"/> 

 

protected void Page_Load(object sender, EventArgs e) { btnDelete.Attributes.Add("onclick","return confirm('确定要删除级的学生吗？')"); }