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英語 高校生

下から5行目のit would~の文構造がわからないです。back upはどのような働きをしているのでしょうか。 教えて頂けるとありがたいです。

A Makeover for Hoover Dam Hydropower has attracted increasing attention in recent years as a renewable type of clean energy. As long as a suitable water source is available, hydropower facilities are usually good investments, producing energy in a manner that generates far less air pollution and CO2 emissions than fossil fuels do. The most common way to generate hydropower is to trap water at a high elevation behind a dam so it can be released and used to spin turbines below, which, in turn, power electricity-producing generators. However, hydropower has its drawbacks. Droughts and increased water consumption have reduced the flow of many rivers. As rivers become shallower, the necessary volume of water for electricity difficult to maintain, and power supply and generation is dependability are negatively impacted. more Variability in water levels has particularly affected Hoover Dam, a mega-scale hydropower facility in the US state of Nevada. Built in the 1930s at enormous expense to control the frequently flooding Colorado River and maintain a water supply for farmland irrigation, the dam's hydropower capabilities were seen as a way to recover some of the costs of its construction over the long term. The dam's electricity-generating capacity, however, was challenged from the start by seasonal variability in water flow, and in recent years has been greatly reduced by droughts. Combining hydropower with other alternative energy sources, though, may offer a solution. Solar and wind plants can produce enormous amounts of electricity, but one serious downside is that the energy they produce is not available when there is little sun or wind. While conventional batteries can help with this issue, storing such tremendous volumes of electricity has long been a challenge. A recently proposed system for Hoover Dam could provide an answer, though. The plan suggests building a new pumping station that would be powered by both wind and solar. It would push water from the river back up to Hoover Dam, refilling the lake behind it. The water could be released anytime to power the dam's generators in order to reliably meet demand for electricity. Kelly Sanders, an engineering professor at the University of Southern California, is enthusiastic about the storage plan, saying, "We by the p replace fo solat als are st ons to the What is 1 Inst inves 2 WE dams 3 A neg sys 1 en

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英語 高校生

(4)の答えがthe problemでしたがsolving the problemではダメでしょうか?

humans. "We were able to identify one of the many molecular features that likely shape behavior," she adds. ** hol boquete es Though the origins of the dog/human partnership remain unknown, it's becoming increasingly clear that each species has changed (during our long years header The physical differences between a basset hound and wolf are obvious, but dogs have also changed in ways that are more than skin (or fur) deep. One recent study shows how by bonding with us and learning to work ogether with humans, dogs may have actually become worse at working together Their pack lifestyle and mentality appear to be reduced and are far as a species. less prevalent even in wild dogs than in wolves. But, Yale's Laurie Santos says, dogs may have compensated in other interesting ways. They've learned to use humans to solve problems. "Several researchers have presented dogs and wolves with an impossible problem (e.g., a puzzle box that can't be opened or a pulling tool that stops working) and have asked how these different species react," Santos explains. Researchers have found that wolves try lots of different trial and error tactics to solve the problem - they get at it physically. But at the first sign of trouble, dogs do something different. They look back to their human companion for help. This work hints that dogs may have lost some of their physical problem-solving abilities in favor of more social strategies, ones that rely on the unique sort of cooperation

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