"She drives the motorcycle by herself."
Translation:Cô ấy tự lái xe máy.
I highly recommend installing UniKey ( http://www.unikey.org/ ). It uses the Telex system ( https://en.wikipedia.org/wiki/Telex_(input_method) ), which I find easier and more intuitive to use than the Windows Vietnamese keyboard.
On Windows- https://wuhrr.wordpress.com/2014/01/24/how-to-type-vietnamese-on-windows-7/ On Mac (and with a better explanation of how the Vietnamese keyboard works)- http://vietnamese-language.com/how-to-type-the-vietnamese-alphabet-on-a-mac/