I think it would be helpful if users could mark some cards to have an opportunity of reviewing them more often.
For example, EN->DE course, I got a card "... Donnerwetter!" and the translation for the omitted word "to the". It wasn't too hard to figure out the omitted preposition "zum", but since the phrase is more like an idiom (I like it and I definitelly want to remember it) and I only wrote a preposition, I'm sure that I didn't learn the phrase. Since I answered the question right, the card will not show up so often and I'm affraid that I will forget the phrase too soon.
I can answer wrong the next time I see the card to see it more often, but it looks like cheating, I do know the omitted preposition. The requested feature would definitelly help me.