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    html {
      font-family: sans-serif, FangSong, "仿宋", STKaiti, "华文楷体";
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      position: absolute;
      background: lightslategray;
      width: 240px;
      height: 200px;
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      transform: perspective(600px) rotateY(0deg);
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    .flip3D > .back {
      position: absolute;
      background: Salmon;
      width: 240px;
      height: 200px;
      border-radius: 7px;
      transform: perspective(600px) rotateY(180deg);
      -webkit-transform: perspective(600px) rotateY(180deg);
      -moz-transform: perspective(600px) rotateY(180deg);
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    .flip3D:hover > .front {
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    .flip3D:hover > .back {
      transform: perspective(600px) rotateY(0deg);
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    .chinese {
      text-align: center;
      font-size: 140%;
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    .pinyin {
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    .chinese_long {
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      font-weight: 900;
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    .pinyin_long {
      text-align: center;
      font-size: 90%;
      margin-top:-40px;
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    .chinese_xlong {
      text-align: center;
      font-size: 90%;
      font-weight: 900;
      margin-top: 15px;
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    .pinyin_xlong {
      text-align: center;
      font-size: 95%;
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    }
    div {
      text-align: center;
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</head>

<body>
  <div class="flip3D">
    <div class="back"><h3>always</h3></div>
    <div class="front"><div class="chinese"><h1>总是</h1></div><div class="pinyin"><h3>zǒng&thinsp;shì</h3></div></div>
  </div>
  <div class="flip3D">
    <div class="back"><h3>often</h3></div>
    <div class="front"><div class="chinese"><h1>常常</h1></div><div class="pinyin"><h3>cháng&thinsp;cháng</h3></div></div>
  </div>
  <div class="flip3D">
    <div class="back"><h3>frequently</h3></div>
    <div class="front"><div class="chinese_long"><h1>频繁地</h1></div><div class="pinyin_long"><h3>pín&thinsp;fán&thinsp;de</h3></div></div>
  </div>
  <div class="flip3D">
    <div class="back"><h3>often</h3></div>
    <div class="front"><div class="chinese_long"><h1>经常地</h1></div><div class="pinyin_long"><h3>jīng&thinsp;cháng&thinsp;de</h3></div></div>
  </div>

  <div class="flip3D">
    <div class="back"><h3>normally</h3></div>
    <div class="front"><div class="chinese"><h1>通常</h1></div><div class="pinyin"><h3>tōng&thinsp;cháng</h3></div></div>
  </div>
  <div class="flip3D">
    <div class="back"><h3>usually</h3></div>
    <div class="front"><div class="chinese"><h1>平常</h1></div><div class="pinyin"><h3>píng&thinsp;cháng</h3></div></div>
  </div>
  <div class="flip3D">
    <div class="back"><h3>sometimes</h3></div>
    <div class="front"><div class="chinese"><h1>有时</h1></div><div class="pinyin"><h3>yǒu&thinsp;shí</h3></div></div>
  </div>
  <div class="flip3D">
    <div class="back"><h3>occasionally</h3></div>
    <div class="front"><div class="chinese"><h1>偶尔</h1></div><div class="pinyin"><h3>ǒu&thinsp;ěr</h3></div></div>
  </div>

  <div class="flip3D">
    <div class="back"><h3>seldom, rarely</h3></div>
    <div class="front"><div class="chinese"><h1>很少</h1></div><div class="pinyin"><h3>hěn&thinsp;shǎo</h3></div></div>
  </div>
  <div class="flip3D">
    <div class="back"><h3>never</h3></div>
    <div class="front"><div class="chinese"><h1>从不</h1></div><div class="pinyin"><h3>cóng&thinsp;bù</h3></div></div>
  </div>

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