He was able to do that so easily because he built it on top of Facebook, and Facebook was built on top of the web, and that was built on top of the Internet, and so on and so forth.
他可以这么轻松的完成 是因为这个应用是在脸书上搭建起来的， 而脸书又依托于网络， 而网络又是在互联网上建造起来的， 等等等等。