Verb conjugation of "andauern" in German

There is a small misunderstanding about the homework. I can do them, but they will be too confusing? I am trying to find the article from where I took the sentences in order to ease the task for all students.
Productivity declines when it is too hot outside. Oscar therefore closed his laptop and production unit and headed towards the lake where his pretty girlfriend was waiting for him. Once he arrived he bought a ice cream as a surprise.
I need to learn a lot of Spanish because I want to study at the university of Madrid. In Switzerland, I studied law, but after 2 years I have switched to medicine: to help people, rather than you know....