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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

この文章の4行目にある、because they would harm whatever bacterial life forms might be present on the planet の文構造についてなのですが、might の前にあるはずの関係代名詞の主格whi... 続きを読む

次の文章を読んで、 問1~4に答えなさい。 The establishment of a colony on Mars has been a dream for decades. Inevitably some people have objected to the idea of colonizing Mars on both ideological and practical grounds. Some object to humans living on Mars because they would harm whatever bacterial life forms might be present on the planet. Others oppose Mars settlements because they disagree with the idea of using the Red Planet as a "backup" in case the Earth is destroyed. Those in favor of colonizing Mars, however, look to spread the human race beyond our single planet. The practical considerations of surviving long term on a world without a breathable atmosphere, no surface water, exposure to radiation, and extremes of heat and cold all have to be addressed first. Mars colonists could survive in domed cities, extracting and recycling resources from the Martian environment. However, a more interesting plan for the settlement of the Red Planet involves a process called terraforming, turning the dangerous environ- ment of Mars into something resembling Earth. Billions of years ago, Mars was more like Earth, with a thick atmosphere as well as oceans and rivers of surface water. The planet may well have had complex life forms. However, sometime in the distant past, Mars lost its (A ). When Mars found itself without the protection of that field, solar wind relentlessly stripped it of its atmosphere, quickly turning the planet into the frozen desert it currently is. While a number of schemes exist to restore Mars' atmosphere, creating a runaway greenhouse process that would raise its temperature, NASA and some academic researchers recently came up with a simple way to achieve the process naturally. The idea involves the creation of an electromagnetic shield between Mars and the Sun to protect the Red Planet from solar wind. Without the solar wind stripping it away, the atmosphere of Mars would gradually become thicker. Soon the temperature on the Martian surface would become high enough to release the trapped ( B ) at the poles, accelerating the (C). Water ice at the poles would melt, giving Mars back some measure of its oceans and rivers. All humans would have to do is introduce

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