var radioNum      = 20
var CorrectAnswer = "CBCCACACABBCAAAACBBA"
var answers ="(1)C  (2)B  (3)C  (4)C  (5)A \r\n(6)C  (7)A  (8)C  (9)A  (10)B \r\n(11)B  (12)C  (13)A  (14)A  (15)A \r\n(16)A  (17)C  (18)B  (19)B  (20)A"
var CompareAnswer = "ABC"
var radioTax      = 100 / radioNum
var CheckPoint    = new Array(radioNum)
for (i=0; i<radioNum; i++)
  CheckPoint[i]  = i*3 + CompareAnswer.indexOf(CorrectAnswer.charAt(i))
var completed = 0

function CheckSum ()
  {
  var YourScore = 0
  completed = 1
  for (i=0; i<radioNum; i++)
    {
    if (document.ANSWER.elements[CheckPoint[i]].checked == true)
      {
      YourScore += radioTax
      }
    }
  MyPress = "此次測驗成績: " + YourScore + " 分\r\n"
  if      (YourScore == 100) { MyPress += "Excellent!! 一百分耶!! 完美的成績!!" }
  else if (YourScore >= 80)  { MyPress += "Good!! 優等的成績. 你很用功喔!" }
  else if (YourScore >= 60)  { MyPress += "It's OK. 別灰心, 還可以加油喔~~" }
  else                       { MyPress += "ummmm... 好像這次成績不太好喔?? 下次再加油!!" }
  alert(MyPress)
  }

function answerbox()
{
  if (completed == 0 )
       { alert("哈囉，請作完題目再看答案，好嗎？") }
  else { alert(answers) }
}