"I have a test tomorrow."

Thanks for letting us know. We are looking into this now :)

Edit This error is because Duolingo recently changed how hints are handled. They are still in the process of finalising this and so there will be a few hiccups until it is complete. I will keep an eye on this :)

Edit 2 This is now fixed for this particular case. If you see anything else odd please let us know :)