I'm having the same problem on all these types of questions so I get them all wrong about 9 times in a row (when it keeps giving me the question so I'll get it right.) Then, suddenly it gives me all the words and I can get it right. Each time the question is the same, the Discussion page for it leads me to the same page, yet the words given for me to choose from are different. There must be some weird bug for these types of questions. :( I'm using Firefox windows on a laptop.
Throughout Duo it is important to understand that the proper translations are not meant to depend upon using only expressions you have heard. That is part of the challenge, but also one of the strengths of this program. When you can recognize seemingly odd statements and still faithfully reproduce them (while using correct grammar and a similar sentence structure) you'll be well on your way to becoming fluent.
This question is problematic. Reading the other comments will help. Basically the problem is "what is the CONTEXT of the sentence"? Are you saying "Is the week INTERESTING" as opposed to boring; or, are you saying "Is the WEEK interesting" as opposed to any other week. That is not clear in the question so to answer precisely is very difficult. Perhaps DL should allow both answers.