Modify the default pip version to the method corresponding to python2.7

python2.7 and python3.5 are now available in the system

The terminal input python also pops up python2.7 information

But if you type pip-V, what pops up is the one corresponding to pip3.5

So here's the solution

wget https://pypi.python.org/packages/11/b6/abcb525026a4be042b486df43905d6893fb04f05aac21c32c638e939e447/pip-9.0.1.tar.gz#md5=35f01da33009719497f01a4ba69d63c9

tar -xvf pip-9.0.1.tar.gz

cd pip-9.0.1

python setup.py build

python setup.py install