I just reinstall Ubuntu, then i tried to install “Interface for toggling the power on nVidia Optimus video card” & “NVidia Optimus support” in Ubuntu Software Center and can’t found it.

Then i tried sudo add-apt-repository ppa:bumblebee/stable. It went fine however when sudo gedit /etc/apt/sources.list.d/bumblebee-stable-precise.list, the list blank. Nothing.