python使用requests时报错requests.exceptions.SSLError: HTTPSConnectionPool

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\api.py", line 72, in get
return request('get', url, params=params, **kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\api.py", line 58, in request
return session.request(method=method, url=url, **kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 508, in request
resp = self.send(prep, **send_kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 640, in send
history = [resp for resp in gen] if allow_redirects else []
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 218, in resolve_redirects
**adapter_kwargs
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 618, in send
r = adapter.send(request, **kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\adapters.py", line 506, in send
raise SSLError(e, request=request)
requests.exceptions.SSLError: HTTPSConnectionPool(host='www.baidu.com', port=443): Max retries exceeded with url: / (Caused by SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:581)'),))

>>> import requests
>>> requests.get('http://www.baidu.com/')
<Response [200]>
>>> requests.get('http://www.baidu.com/')
<Response [200]>
>>> requests.get('http://www.baidu.com/')
<Response [200]>
>>> header = {'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1',}
>>> requests.get('http://www.baidu.com/', headers = header)
<Response [200]>

>>> header = {'User-Agent': 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.1',}
>>> requests.get('http://www.baidu.com/', headers = header)
<Response [200]>
>>> requests.get('http://www.baidu.com/', headers = header)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\api.py", line 72, in get
return request('get', url, params=params, **kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\api.py", line 58, in request
return session.request(method=method, url=url, **kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 508, in request
resp = self.send(prep, **send_kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 640, in send
history = [resp for resp in gen] if allow_redirects else []
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 218, in resolve_redirects
**adapter_kwargs
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\sessions.py", line 618, in send
r = adapter.send(request, **kwargs)
File "D:\python\lib\site-packages\requests-2.18.3-py2.7.egg\requests\adapters.py", line 506, in send
raise SSLError(e, request=request)
requests.exceptions.SSLError: HTTPSConnectionPool(host='www.baidu.com', port=443): Max retries exceeded with url: / (Caused by SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:581)'),))

>>> response = requests.get('http://www.baidu.com/', headers = header, verify=False)
D:\python\lib\site-packages\urllib3\connectionpool.py:858: InsecureRequestWarning: Unverified HTTPS request is being made. Adding certificate verification is strongly advised. See: https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
InsecureRequestWarning)
>>> response.history
[<Response [302]>]
>>> response.url
u'https://www.baidu.com/'

>>> response = requests.get('http://www.baidu.com/', verify=False)
>>> response.history
[]
>>> response.url
u'http://www.baidu.com/'