German UBI exam trainer

The Radiophone Operator's Certificate for the Radiotelephone Service on Inland Waterways (UBI, UKW-Sprechfunkzeugnis für den Binnenschifffahrtsfunk) is a German licence required to operate radiotelephone stations. It allows participation in the radiotelephone service on inland waterways.
This App supports you in training the questions you get asked in the written test. The test has to be taken in the German language. Therefore the questions in this application are German as well.
All questions have to be answered correctly five times. If a question gets answered wrong, one correct answer is subtracted again. The UBI trainer remembers when you have answered a question the last time. It extends the interval after which a question is asked again after each correct answer. This ensures, that you learn the questions effectually.