This is the most convenient tools I have ever used. Thank Huang for your creative idea. It will be better if there is an option for users to change the dictionary and to capture accurately in the PDF files. Now it only captures the first two words of the line in PDF files.

Finally the ultimate English Words Learning tool for ANKI users arrived on Firefox. Like the old day's "Backword", this is far more powerful and usable add-on.

This is a must have add-on. Please try it.