var json3 =([
  {
    "qnum": 0,
    "correct": 2,
    "qtext": "Q1.下面哪个图表是正确的？",
    "optionA": "A.",
    "optionB": "B.",
    "optionC": "C.",
    "answers": [
      "小提示：指南针的指针受到北极的排斥.",
      "正确！磁感线由北极分布向南极。很好——来试试问题2.",
      "小提示：指南针的指针受到北极的排斥."
    ]
  },
  {
    "qnum": 1,
    "correct": 1,
    "qtext": "Q2.哪个图表显示出了两个磁体之间正确的磁感线的图形？",
    "optionA": "A.",
    "optionB": "B.",
    "optionC": "C.",
    "answers": [
      "正确！磁感线从磁铁的北极指向南极.",
      "小提示：磁感线从北极指向南极.",
      "小提示：磁感线从北极指向南极."
    ]
  }
]);
