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PHPzCorrection status：qualified
Teacher's comments：代码书写习惯可以改一改，js代码一般放入body标签的结束之前
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<!DOCTYPE html><html><head><meta charset="utf-8"><title>计算器</title></head><body><script>function fn(){var od1= document.getElementById('d1').valueod1=parseFloat(od1)var od2= document.getElementById('d2').valueod2=parseFloat(od2)var od3=document.getElementById('d3')var oysf=document.getElementById('ysf').valueif(oysf=='+'){od3.value=od1+od2}else if(oysf=='-'){od3.value=od1-od2}else if(oysf=='*'){od3.value=od1*od2}else {od3.value=od1/od2}}</script><input id="d1" type="text" value=""><select id="ysf"><option value="+">+</option><option value="-">-</option><option value="*">*</option><option value="÷">/</option></select><input id="d2" type="text" value=""><span>=</span><input type="text" id="d3" value=""><button onclick="fn()">点击计算</button></body></html>
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