Are you employed by Duo ? Amazing to see youngsters learn so many languages at the time ? Quite irrealistic as a matter of fact .I'm 63 and have been Learning 5 languages , there was no DUO LINGo back then . Duo is truly addictive but it can only be a start in the Learning of a foreign language .The Learning itself is more demanding and takes YEARS in order to be really fluent .
I don't think anybody claims that you can learn a language solely with Duolingo. Particularly building sentences oneself and real conversation situations are not supported. That's why questions about what level (A1, A2, B1, B2, C1, C2) you can reach by Duolingo are answered by realistic participants that it can best be A2 or B1, but even that with serious lacks.
But Duolingo definitely can help. I, for example, have had prior knowledge of all the languages I speak before I met Duolingo. But it definitely helped me improve or reactivate.
Of course I suggest to use other ressorces in parallel, particularly a good grammar book and a good dictionary.
http://www.merriam-webster.com/dictionary/disapprove Not approving of someone is not the same as being actively against that person. http://www.merriam-webster.com/dictionary/against
My previous exercise was, "Der Hund läuft gegen die Wand." Gegen was used in the sense of proximity, not in the adversarial sense. This is in contrast to the advice posted here. Please advise if there is an exception rule, or if the dog's greatest adversary is the wall. Thank you!
"sie" means "her" or "them". "Sie" meaning you is always capitalized. http://german.about.com/od/grammar/a/Germanyou.htm
Scroll down to the Formal you "Sie": http://german.about.com/library/blcase_sum2.htm