TASK DEFINITION: In this task, you're given passages that contain mentions of a time duration related quesry and we are supposed to write answer to a question that involves event “frequency", which refers to how often an event is likely to be repeated. For example, "taking showers" typically occurs ~5 times a week, "going to saturday market" usually happens every few weeks/months, etc. 
 Note that a lot of the questions could have more than one correct answers. We only need a single most-likely answer. Please try to keep your "answer" as simple as possible. Concise and simple "answer" is preferred over those complex and verbose ones.  
PROBLEM: Sentence: The Council does not have executive powers but meets biannually to discuss issues of mutual importance. Similarly, the Parliamentary Assembly has no legislative powers but investigates and collects witness evidence from the public on matters of mutual concern to its members. Reports on its findings are presented to the Governments of Ireland and the United Kingdom. During the February 2008 meeting of the British–Irish Council, it was agreed to set up a standing secretariat that would serve as a permanent 'civil service' for the Council. Leading on from developments in the British–Irish Council, the chair of the British–Irish Inter-Parliamentary Assembly, Niall Blaney, has suggested that the body should shadow the British–Irish Council's work. 
Question: How often does the British-Irish Council meet?

SOLUTION: biannually

PROBLEM: Sentence: The major issue with the term Hellenistic lies in its convenience, as the spread of Greek culture was not the generalized phenomenon that the term implies. Some areas of the conquered world were more affected by Greek influences than others. The term Hellenistic also implies that the Greek populations were of majority in the areas in which they settled, while in many cases, the Greek settlers were actually the minority among the native populations. The Greek population and the native population did not always mix; the Greeks moved and brought their own culture, but interaction did not always occur. 
Question: How often did Greek population and natives mix?

SOLUTION: not always

PROBLEM: Sentence: Specialized comics periodicals formats vary greatly in different cultures. Comic books, primarily an American format, are thin periodicals usually published in colour. European and Japanese comics are frequently serialized in magazines—monthly or weekly in Europe, and usually black-and-white and weekly in Japan. Japanese comics magazine typically run to hundreds of pages. 
Question: How often are European serialized comics in magazines?

SOLUTION:
monthly or weekly