Context and question: 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?
Answer: unanswerable
Context and question: A more recent study by science historian John van Wyhe has determined that the idea that Darwin delayed publication only dates back to the 1940s, and Darwin's contemporaries thought the time he took was reasonable. Darwin always finished one book before starting another. While he was researching, he told many people about his interest in transmutation without causing outrage. He firmly intended to publish, but it was not until September 1854 that he could work on it full-time. His estimate that writing his "big book" would take five years was optimistic.
What was Darwin's process on writing his books?
Answer: Darwin always finished one book before starting another
Context and question: During his tour on the guided missile frigate USS Gridley, Kerry requested duty in South Vietnam, listing as his first preference a position as the commander of a Fast Patrol Craft (PCF), also known as a "Swift boat." These 50-foot (15 m) boats have aluminum hulls and have little or no armor, but are heavily armed and rely on speed. "I didn't really want to get involved in the war", Kerry said in a book of Vietnam reminiscences published in 1986. "When I signed up for the swift boats, they had very little to do with the war. They were engaged in coastal patrolling and that's what I thought I was going to be doing." However, his second choice of billet was on a river patrol boat, or "PBR", which at the time was serving a more dangerous duty on the rivers of Vietnam.
What kind of ship was the USS Gridley?
Answer:
guided missile frigate