用etree解析文件夹中xml文件报错是为什么呀？

我看了一段别人写的代码，用etree解析xml文件中的xmin，xmax等参数。别人都能解析出参数，而我这里却报错。

def to_labels(path):
    xml = open('{}'.format(path)).read()
    sel = etree.HTML(xml)
    width = int(sel.xpath('//size/width/test()')[0])
    height = int(sel.xpath('//size/height/test()')[0])
    xmin = int(sel.xpath('//bndbox//xmin/test()')[0])
    ymin = int(sel.xpath('//bndbox//ymin/test()')[0])
    xmax = int(sel.xpath('//bndbox//xmax/test()')[0])
    ymax = int(sel.xpath('//bndbox//ymax/test()')[0])
    return [xmin, ymin, xmax, ymax]

labels = [to_labels(path) for path in xmls]

解析过后报错：
**__XPathEvalError Traceback (most recent call last)
in ()
----> 1 labels = [to_labels(path) for path in xmls]

in (.0)
----> 1 labels = [to_labels(path) for path in xmls]

in to_labels(path)
2 xml = open('{}'.format(path)).read()
3 sel = etree.HTML(xml)
----> 4 width = int(sel.xpath('//size/width/test()')[0])
5 height = int(sel.xpath('//size/height/test()')[0])
6 xmin = int(sel.xpath('//bndbox//xmin/test()')[0])

src/lxml/etree.pyx in lxml.etree._Element.xpath()

src/lxml/xpath.pxi in lxml.etree.XPathElementEvaluator.__call__()

src/lxml/xpath.pxi in lxml.etree._XPathEvaluatorBase._handle_result()

XPathEvalError: Invalid expression**__

请问有大神知道是什么原因么

https://blog.csdn.net/mdjxy63/article/details/75578130?utm_source=blogxgwz2