abstract：<script type="text/javascript">var x=5;var y=7;document write(x+y);//顯示12<script>
<script type="text/javascript">
var x=5;
var y=7;
document write(x+y);//顯示12
<script>
Correcting teacher：滅絕師太Correction time：2019-01-06 09:27:12
Teacher's summary：定義變量的注意事項要搞搞清楚喲！基礎的知識點比較重要！