如何在Scrapy中使用xpath抓取没有类或属性的标记？

from scrapy import Selector

html_content = response.body

selector = Selector(text=html_content)

target_elements = selector.xpath('//tag_name')

text = target_elements.xpath('string()').get()
attribute = target_elements.xpath('@attr_name').get()

child_elements = target_elements.xpath('.//child_tag_name')

for child_element in child_elements:
    child_text = child_element.xpath('string()').get()
    child_attribute = child_element.xpath('@attr_name').get()