Firefox plugin for English learners

Solution 1:

Does the backword add-on help?

Backword helps people learning English by mouse-over pop-up translation and easily new-words collection.

Features:

• Translate an English word into French, German, Spanish, Russian, Italian, Japanese, Korean,
  Traditional or Simplified Chinese when mouse cursor hovers over it.
• With one click, remember all context of the word, such as URL of the page and the paragraph which the word belongs to.
• Get Pronunciation of the word with one click.
• Write a note for the word.
• Search more explanation of the word with one click.
• Review all words and context collected on a build-in page.