If you want to review the words or sentences you have previously learned, you need to:
1. Go to the "You" tab.
2. Tap on "Review".
3. Choose what you want to review: Words or Sentences.
4. Tap on the "Time" tab.
5. Choose one of the available options, according to how much time has passed since you learned the words or sentences you want to review.
6. Tap the "Review" button.