<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.third_cols_table tbody tr td:nth-child(1) {
color: red;
};
.third_cols_table tbody tr td:nth-child(2) {
color: aqua;
};
.third_cols_table tbody tr td:nth-child(3) {
color: blue;
};
</style>
</head>
<body>
<div>
<table class="third_cols_table">
<tr>
<td>名称</td>
<td>数量</td>
<td>单价</td>
</tr>
</table>
</div>
</body>
</html>就第一个td 变红，其他td没反应，我真的没明白到底为啥？？？？？？
