Yeah, I searched serveal same problem(like how to install homebrew on MacOSx) in StackOverflow, but problem still occurs:
curl: (6) Could not resolve host: raw.githubusercontent.com
The command I typed in the terminal comes from homebrew.
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
But failed to install homebrew.