Problem: Railway electrification system:

Central station electricity can often be generated with higher efficiency than a mobile engine/generator. While the efficiency of power plant generation and diesel locomotive generation are roughly the same in the nominal regime, diesel motors decrease in efficiency in non-nominal regimes at low power  while if an electric power plant needs to generate less power it will shut down its least efficient generators, thereby increasing efficiency. The electric train can save energy (as compared to diesel) by regenerative braking and by not needing to consume energy by idling as diesel locomotives do when stopped or coasting. However, electric rolling stock may run cooling blowers when stopped or coasting, thus consuming energy.

Electric rolling stock may use heating blowers when?
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A: unanswerable


Problem: Sichuan:

The Yangtze River and its tributaries flows through the mountains of western Sichuan and the Sichuan Basin; thus, the province is upstream of the great cities that stand along the Yangtze River further to the east, such as Chongqing, Wuhan, Nanjing and Shanghai. One of the major tributaries of the Yangtze within the province is the Min River of central Sichuan, which joins the Yangtze at Yibin. Sichuan's 4 main rivers, as Sichuan means literally, are Jaling Jiang, Tuo Jiang, Yalong Jiang, and Jinsha Jiang.

Name some cities downstream of the Yangtze river that are to the west of Sichuan?
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A: unanswerable


Problem: Oklahoma City:

Other major sporting events include Thoroughbred and Quarter horse racing circuits at Remington Park and numerous horse shows and equine events that take place at the state fairgrounds each year. There are numerous golf courses and country clubs spread around the city.

What park hosts Quarter horse racing?
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A: Remington Park


Problem: Race (human categorization):

Morning (2008) looked at high school biology textbooks during the 1952-2002 period and initially found a similar pattern with only 35% directly discussing race in the 1983–92 period from initially 92% doing so. However, this has increased somewhat after this to 43%. More indirect and brief discussions of race in the context of medical disorders have increased from none to 93% of textbooks. In general, the material on race has moved from surface traits to genetics and evolutionary history. The study argues that the textbooks' fundamental message about the existence of races has changed little.

How many of the textbooks between 1983 and 1992 discussed race?
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A:
35%