Problem: Additionally, there are issues of connections between different electrical services, particularly connecting intercity lines with sections electrified for commuter traffic, but also between commuter lines built to different standards. This can cause electrification of certain connections to be very expensive simply because of the implications on the sections it is connecting. Many lines have come to be overlaid with multiple electrification standards for different trains to avoid having to replace the existing rolling stock on those lines. Obviously, this requires that the economics of a particular connection must be more compelling and this has prevented complete electrification of many lines. In a few cases, there are diesel trains running along completely electrified routes and this can be due to incompatibility of electrification standards along the route.
Why the commuter lines built to different standards can cause be complicated?
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Answer: the implications on the sections it is connecting

Problem: Colin Humphreys and W. G. Waddington of Oxford University considered the possibility that a lunar, rather than solar, eclipse might have taken place. They concluded that such an eclipse would have been visible, for thirty minutes, from Jerusalem and suggested the gospel reference to a solar eclipse was the result of a scribe wrongly amending a text. Historian David Henige dismisses this explanation as 'indefensible' and astronomer Bradley Schaefer points out that the lunar eclipse would not have been visible during daylight hours.
What event did David Henige believe might have happened instead of a solar eclipse?
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Answer: unanswerable

Problem: The bombing failed to demoralise the British into surrender or significantly damage the war economy. The eight months of bombing never seriously hampered British production and the war industries continued to operate and expand. The Blitz was only authorised when the Luftwaffe had failed to meet preconditions for a 1940 launch of Operation Sea Lion, the provisionally planned German invasion of Britain. By May 1941 the threat of an invasion of Britain had passed, and Hitler's attention had turned to Operation Barbarossa in the East. In comparison to the later Allied bombing campaign against Germany, the Blitz resulted in relatively few casualties; the British bombing of Hamburg in July 1943 inflicted some 42,000 civilian deaths, about the same as the entire Blitz.
Who was the leader of the Luftwaffe?
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Answer:
Hitler