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Q: How have changing perceptions of oil's usefulness made it more valuable over time?
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In a selection sort when changing from ascending to descending order only---------- modifications need to be made to the algorithm?

Change every "<" to ">" and ">" to "<" .

Why were most of the early Chinese inventions related to agriculture?

Chinese inventions made life easier for farmers and made more grain available for trade. For example, a better plow and farm tools helped increase crop production. The invention of a collar harness allowed horses to pull heavy loads. The wheelbarrow made it easier for farmers to move heavy loads by hand. Watermills used river power to grind grain. In a land of mostly farmers, these inventions were valuable.

Why it is necessary to disconnect the load when change the tap?

when the load is connected to draws some current. while changing the tap of the transformer the tappings related to the winding is changed , so the load current affects the transformer. hence while changing the tap it should be noted thatAnswerThere are two types of tap-changing mechanism -'off-load' and 'on-load'. Off-load tap changers physically disconnect the winding when changing from one tap setting to the next. Accordingly, the circuit is temporarily broken, and dangerous arcing will take place if the transformer is energised. Therefore off-load tap changers require that the transformer is disconnected while the mechanism is operated.On the other hand, 'on-load' tap changers use a mechanism which incorporates a 'make before break' contact arrangement, ensuring that no break is made in the circuit as the mechanism moves from one tap setting to the next, enabling it to operate with the transformer energised and supplying load. On-load tap changers are usually automatically operated, although this feature can be overridden and operated manually.

What is the difference between made of and made from?

"Made of" and "Made from" can mean the same thing. "That can is made from aluminum." "That can is made of aluminum." However, they can't be used the same in every situation. You can say: "That house is made of wood and made from workers." But you can't say: "That house is made of workers and made from wood."

Who made the abacus and what other machines did he or she made?

the chinese and they made the wheel barrow