如何获取父节点和仅一个子节点

Lets say I have this xml:

让我说我有这个xml：

<categories>
    <category text="Arts">
            <category text="Design"/>
            <category text="Visual Arts"/>
    </category>
    <category text="Business">
            <category text="Business News"/>
            <category text="Careers"/>
            <category text="Investing"/>
    </category>
    <category text="Comedy"/>
</categories>
<cate