<html><body><h1>演示如何访问复选框</h1>复选框：<input type="checkbox" id="myCheck"><p>点击“试一试”按钮可勾选复选框。</p><button onclick="myFunction()">试一试</button><script>function myFunction() { var x = document.getElementById("myCheck"); x.checked = true;}</script></body></html>