题目内容
（请给出正确答案）
from scrapy.selector import Selector htmlText="A1B...
from scrapy.selector import Selector htmlText="A1B1＜c＞C1＜/c＞＜d＞D＜e＞E＜/e＞＜/d＞B2＜c＞C2＜/c＞" selector=Selector(text=htmlText) s=selector.xpath("//a/preceding-sibling::*") print(s.extract()) s=selector.xpath("//b/preceding-sibling::*[position()=1]") print(s.extract()) s=selector.xpath("//b[position()=2]/preceding-sibling::*") print(s.extract()) ___________________________________________________________________ print(s.extract()) 程序结果： [] ['A1', '＜d＞D＜e＞E＜/e＞＜/d＞'] ['A1', 'B1', '＜c＞C1＜/c＞', '＜d＞D＜e＞E＜/e＞＜/d＞'] ['＜d＞D＜e＞E＜/e＞＜/d＞']
A、s=selector.xpath("//b[position()=1]/preceding-sibling::*[position()=2]")
B、s=selector.xpath("//b[position=1]/preceding-sibling::*[position=2]")
C、s=selector.xpath("//b[position=2]/preceding-sibling::*[position=1]")
D、s=selector.xpath("//b[position()=2]/preceding-sibling::*[position()=1]")
如搜索结果不匹配，请 
