I've just uploaded a bunch of changes to the way the example sentences (which are in alpha testing right now) work. I was persuaded to set it up such that you have to choose an example sentence from the word popup before you will start to be prompted with it--that way it's not just another background thing slowing you down, but rather something you've actively considered.
To get to the word popup to choose a sentence, then, you either press "D" or "K" or click the word's magnifying glass in the prompt.
You can now also click on any word in an example sentence to get its word popup, in case you didn't know it, and from there you could add it to your studies.
Alpha testers, let me know when you find bugs and ways it can be improved--thanks! Barring anything major, I'll put it into beta in a couple days and everyone can try it.