Translate the following sentence into German: "I have been playing the piano for five years."

Answer: "Ich spiele seit fünf Jahren das Klavier". A common mistake made by students of German would be to say: "Ich habe seit fünf Jahren das Klavier gespielt". This is because the concept of an ongoing action started at a specified point in the past is expressed using "have been + -ing" in English (i.e. the present perfect progressive, but don't worry about the technical name for now), whereas in German the simple present is used.