I suffer a strange "bug" in this 3rd lesson in the topic Adverbs. It seems that the phrases with "שוב" and "/לעתים נדירות" or "רחוקות" didn't appear in my app in the smartphone, but just in the computer.
The first time when I did this lesson in the cell phone, I found those words in the practice without being studied them first, which was surprising. Later I realized that they were suppposed to be learned in this lesson, and in fact they are in duolingo.com in the computer.
You can download the old version and it is possible to repeat the lesson you want.
Here is the link of the last version where it was possible to choose the lesson one wanted:
it's like a glass half-full, half-empty situation: "Rarely" means "almost never," "once in a while" means "almost sometimes." If you were going to a restaurant on the other side of town with somebody who's already been, you'd hear "I rarely go there, so I can't vouch for the quality of the food," but "I go there once in a while; let me pick your meal out for you, you won't regret it!"