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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

お願いしますm(_ _)m

Grammar Focus (ポイント) 「~までに(は)」 I by ★行為や動作の完了の時点だが、「ぎりぎり」の意味を示す Thave to get home by midnight on Saturday nights. 「私は土曜日の夜は真夜中までに帰って来なければなりません」 until (till) ★継続した状態の終点を示す I stay up until midnight on Saturday nights. 「私は土曜日の夜は真夜中まで起きています」 I before 「~前に」 ★漠然と「前」 を示す I wake up before noon on Sundays. 「私は日曜日には正午前には目を覚まします」 B) Conversations [ポイント)を学び、 次の会話の日本文に合うように、( 1. A: 食器をさげるバイトをやっているんだよ。 B: 放課後毎晩? それとも週末だけ? A:土曜と日曜の11時から4時までだよ。 A: I have a ( )-time job and bus dishes. ) school or only on ( B: Every night ( A: I do it on Saturdays and Sundays from eleven ( 2. A: 僕は、来年の今ごろになってもまだ失業中だと思う? B: もちろん、そんなことないよ。 その頃までにはきっと仕事が見つかっているよ A: Do you think I'll still be (sh B: No, of course ( ) that ( )内に適当な一語を入れなさい。 A: ( B: No, let's wait ( there anytime ( ) we go now? ) this time next year? ). I'm sure you'll have found a job 3. A: さあ出かけようか。 B : いや、雨が止むまで待とうよ。 今晩の10時前に着けばいいんだから。 ) four. ) it stops ( ) ten tonight. ). It's all right to get

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