If the user open firefox,  select "File" -> "print", it can not print English web page.

The solution is below:

1. Open Firefox and select "Edit->Perferences"

2. Choose "Content" and then change the Default Font to `serif`

3. Click "Advanced" button which is on the right of "Font & Colors" tab and remove the selection of "Allow pages to choose their own fonts, instead of my selections above".