You've already learned the most common ways of constructing questions in German.

Forming questions with "W" question words

Examples:
Wo waren Sie gestern?
Was suchen Sie?

Yes/no questions, in which the verb is in the first position.

Examples:
Waren Sie gestern in Bochum?
Suchen Sie das Orakel?

You can also easily turn declarative sentences into questions by adding certain fragments of speech at the end, known as tags. They tend to be used to encourage or elicit a positive response from the listener. Often the questioner is looking for confirmation to his or her statement. These sorts of tag questions suggest that the speaker perceives the statement to be correct.

Examples:
Dr. Anderson:
Sie suchen Ostrowski, habe ich recht?
Sie waren gestern in Bochum, oder?
Sie suchen das Orakel, stimmt’s?

Other tags include "nicht wahr?", "nicht?" and "richtig?". In the examples above, Dr. Anderson uses tag questions to get Harry to confirm his suspicions. He's convinced that he already knows the truth. So in this case he seems to be trying to provoke Harry more than anything else.