Q: The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre. It is typically rendered graphically as a plot, and the data observed from each side of a spiral galaxy are generally asymmetric, so that data from each side are averaged to create the curve. A significant discrepancy exists between the experimental curves observed, and a curve derived from theory. The theory of dark matter was postulated to account for the variance.

Answer this question: what is the rotation curve of a spiral galaxy?
A: a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy 's centre. How to explain the answer? To answer the above question, the relevant sentence is: The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's centre.

Q: The series debuted on July 12, 2002, on USA Network. It continued for eight seasons, with the final season concluding on December 4, 2009. The series held the record for the most-watched scripted drama episode in cable television history from 2009 through 2012 (broken by The Walking Dead) with "Mr. Monk and the End -- Part II", its series finale, with 9.4 million viewers, 3.2 million of them in the 18 -- 49 demographic.

Answer this question based on the passage: what year did monk go off the air?
A: 2009. How to explain the answer? This is the relevant information: It continued for eight seasons, with the final season concluding on December 4, 2009.

Q: Passage: Iceland is an island country at the confluence of the North Atlantic and Arctic Oceans, east of Greenland and immediately south of the Arctic Circle, atop the constructive boundary of the northern Mid-Atlantic Ridge about 860 km (530 mi) from Scotland and 4,200 km (2,600 mi) from New York City. One of the world's most sparsely populated countries, Iceland's boundaries are almost the same as the main island -- the world's 18th largest in area and possessing almost all of the country's area and population.

Question: Based on this passage, what type of plate boundary does iceland lie on?
A: the constructive boundary of the northern Mid-Atlantic Ridge. How to explain the answer? The relevant information is: Iceland is an island country at the confluence of the North Atlantic and Arctic Oceans, east of Greenland and immediately south of the Arctic Circle, atop the constructive boundary of the northern Mid-Atlantic Ridge about 860 km (530 mi) from Scotland and 4,200 km (2,600 mi) from New York City.

Q: In the sport of cricket, a hat-trick is an occasion where a bowler takes three wickets in consecutive deliveries. As of 31 July 2017, this feat has only been achieved 43 times in more than two thousand Test matches, the form of the sport in which national representative teams compete in matches of up to five days' duration. The first Test hat-trick was recorded on 2 January 1879, in only the third Test match to take place, by the Australian pace bowler Fred Spofforth, nicknamed "The Demon Bowler", who dismissed three English batsmen with consecutive deliveries at the Melbourne Cricket Ground. The most recent bowler to achieve the feat was English spin bowler Moeen Ali against South Africa on 31 July 2017. At least one bowler from each of the ten nations that have played Test cricket have taken a Test hat-trick.

Based on this passage, first bowler to take hattrick in test cricket?
A:
the Australian pace bowler Fred Spofforth , nicknamed '' The Demon Bowler ''. How to explain the answer? To answer the question, consider the following: The first Test hat-trick was recorded on 2 January 1879, in only the third Test match to take place, by the Australian pace bowler Fred Spofforth, nicknamed "The Demon Bowler", who dismissed three English batsmen with consecutive deliveries at the Melbourne Cricket Ground.