python:pip install pandas报错Could not find a version that satisfies the requirement numpy (from versi

#报错：
Could not fetch URL https://pypi.python.org/simple/numpy/: There was a problem confirming the ssl certificate: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:661) - skipping
Could not find a version that satisfies the requirement numpy (from versions: )
No matching distribution found for numpy

##解决方法
使用国内镜像
pip install pandas -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com