user: Why Ramadan's date change every year?

assistant: Ramadan is a month in the Muslim hijri calendar. It's the month were Muslims fast from sunrise to sunset. The hijri calendar is a lunar calendar and therefore it shifts back 10-12 days every calendar year. Muslims confirm the first day of the month after they observe the new moon. And it ends as they observe the new moon for the month of Shawwal.

user: Who directed the premiere episode of season four of Game of Thrones?

assistant: D.B. Weiss, who also co-authored the season four premiere episode, directed "Two Swords."

user: Extract the beginning and ending term of António de Serpa Pimentel from the following text

assistant: António de Serpa Pimentel was the Prime Minister of Portugal from 14 January 1890 to 11 October 1890