function gerarExercicioO02()
{
var comp = ["Button", "CheckBox", "ComboBox", "CheckedListBox", "DateTimePicker", "Label", "LinkLabel", "ListBox", "MaskedTextBox", "NumericUpDown", "ProgressBar", "RadioButton"];  
var x = prompt("Qual eh o seu codigo de aluno? Veja na planilha!");
//alert(comp.length);
alert("Seu componente x="+comp[x%comp.length]);
}
document.getElementById("btO02").onclick=gerarExercicioO02;