English documents are required

[acmol]

We have some documents in English, but there are so many mistakes and they're outdated.

They need to be refined.

Our documents are generated by sphinx-doc, and sphinx-doc has an internationalization support.

So, I think, all the comments should be written in English especially the ones which are the sources of the generated documents. Chinese documents should be generated with the help of sphinx-doc's internationalization support.