Python 如何使用xpath获取子对象的子对象列表？

有一个table元素，其中包含tr元素。而每个tr元素中都有td元素

<table>
<tr>
<td> some data </td>
<td> other data </td>
</tr>
</table>

---

我只想得到第一个tr元素的td元素列表。但我从表中得到了所有td元素的列表。

tdElementsFromFirstTr=trElementFirst.xpath（“//td”）获取所有td

import lxml.html as html


htmlStr = '''<table>
<tr>
<td> some data </td>
<td> other data </td>
</tr>

<tr>
<td> NO </td>
<td> OTHER NO </td>
</tr>

</table>'''

parsed = html.fromstring(htmlStr)

table = parsed.xpath("//table")
trElementFirst = table[0].xpath("tr")[0]  
tdElementsFromFirstTr = trElementFirst.xpath("td")

for each in tdElementsFromFirstTr:
    print (each.text)

import lxml.html as html


htmlStr = '''<table>
<tr>
<td> some data </td>
<td> other data </td>
</tr>

<tr>
<td> NO </td>
<td> OTHER NO </td>
</tr>

</table>'''

parsed = html.fromstring(htmlStr)

table = parsed.xpath("//table")
trElementFirst = table[0].xpath("tr")[0]  
tdElementsFromFirstTr = trElementFirst.xpath("td")

for each in tdElementsFromFirstTr:
    print (each.text)

some data 
other data