<?xml version="1.0" encoding="UTF-8"?>
<students>
    <class a_name = "1606D">
        <student>
            <name>俄罗斯</name>
            <age>18</age>
            <sex>女</sex>
        </student>
        <student>
            <name>张三</name>
            <age>20</age>
            <sex>男</sex>
        </student>
        <student>
            <name>李四</name>
            <age>33</age>
            <sex>不知道</sex>
        </student>
    </class>
    <class a_name = "1606X">
        <student>
            <name>刘依男</name>
            <age>18</age>
            <sex>女</sex>
        </student>
        <student>
            <name>刘浩</name>
            <age>20</age>
            <sex>男</sex>
        </student>
        <student>
            <name>孙宏恩</name>
            <age>33</age>
            <sex>不知道</sex>
        </student>
    </class>
</students>