我的MacOS下有两个python版本，python2.7位于/usr/bin中，而python3.5位于/usr/local/bin中。我将当前路径在终端上指向/usr/local/bin，并尝试通过command pip3 install nose安装鼻子。（pip3已安装在usr / local / bin中），它给出错误为
Could not fetch URL https://pypi.python.org/simple/nose/: There was a problem confirming the ssl certificate: [SSL: TLSV1_ALERT_PROTOCOL_VERSION] tlsv1 alert protocol version (_ssl.c:719) - skipping
Could not find a version that satisfies the requirement nose (from versions: )
找不到与鼻子匹配的分布
但是，当我尝试使用命令pip install nose安装鼻子时，鼻子显示为已在python2.7下安装