Every time I get to the end of this exercise my progress is blocked by a nag screen trying to get me to sign up for a free trial for duolingo PLUS. I click on no thanks and it just presents the same message over and over in an endless loop. I don't want PLUS. I hate being nagged to do something I am not interested in. It spoils the app. I can only return to the learn mode by going back to the home page, and when I get to the end of the next exercise it happens again. Just stop it.