执行python 爬虫脚本时提示bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml. Do you need to install a parser library?

from bs4 import BeautifulSoup
from urllib.request import urlopen
import re

html = urlopen('http://****/').read().decode('utf-8')
#print(html)

soup = BeautifulSoup(html,features='lxml') #提示此行错误
img_links = soup.find_all('img',{'src':re.compile('.*?.jpg')})
for link in img_links:
    print(link['src'])

本人新手小白，百度后，知道原来是自己没有安装html解析器，lxml。python3下 执行 pip3 install lxml 即可。