问无法使用python3.7和pip3.7安装flask

EN

-> python3.7 --version
Python 3.7.2
-> pip3.7 --version
pip 18.1 from /usr/local/lib/python3.7/site-packages/pip (python 3.7)

Collecting flask
  Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x7fad3a9f60b8>: Failed to establish a new connection: [Errno 101] Network is unreachable')': /simple/flask/
  Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x7fad3a9f6128>: Failed to establish a new connection: [Errno 101] Network is unreachable')': /simple/flask/
  Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x7fad3a9f6390>: Failed to establish a new connection: [Errno 101] Network is unreachable')': /simple/flask/
  Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x7fad3a9f6358>: Failed to establish a new connection: [Errno 101] Network is unreachable')': /simple/flask/
  Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.VerifiedHTTPSConnection object at 0x7fad3a9f64e0>: Failed to establish a new connection: [Errno 101] Network is unreachable')': /simple/flask/
  Could not find a version that satisfies the requirement flask (from versions: )
No matching distribution found for flask

python3.7 -m pip install flask