写xpath路劲时,下面总是有红色波浪线

import re
from lxml import etree
import requests
headers = {
    "User-Agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36 Edg/87.0.664.57"
}
url = "https://www.pearvideo.com/"
reponse = requests.get(url=url,headers=headers)
page_text = reponse.text
tree = etree.HTML(page_text)
li_list = tree.xpath('//ul[@id='actwapSlideList']/li')  # 画横线的地方在pcharm中总是有红色波浪线,显示Unresolved reference 'actwapSlideList' 
print(page_text)
li_list = tree.xpath('//ul[@id='actwapSlideList']/li') 

改成

li_list = tree.xpath("//ul[@id='actwapSlideList']/li")