Question

Our cities have never been denser, taller, or busier than they are now, and with that, comes the constant battle for land. But if we look at aerial images of any city center, we can quickly spot plenty of unused space — the rooftops.

So what can we use this precious resource for? In a growing number of high-density cities, some of it is dedicated to recreation — everything from bars and pools, to soccer pitches and running tracks can now be found atop skyscrapers. But when a rooftop offers access to sunlight, there are two more obvious candidates for its use - agriculture and solar power.

Green roofs have been growing in popularity for more than a decade, and in some cases, growing in scale too. Green roofs can provide a habitat for birds and insects in an otherwise hostile environment.

Cities can be several degrees warmer than the surrounding countryside. Green roofs come with the added benefit of mitigating the dreaded urban heat island effect. Trees and green spaces can absorb shortwave radiation, and use it to evaporate water from their leaves — a kind of ‘double cooling’ effect.

With food security and urban nutrition ever-higher on the agenda for the United Nations, there’s also a worldwide movement of using green roofs for hyper-local food production. In regions with suitable climates, hundreds of different vegetables, fruits, and salad leaves can be grown on rooftops.

But what about solar power? With so many cities now stopping using fossil fuels, and the costs of solar panels dropping dramatically, PV systems have become the ‘go to’ option for generating distributed power in built-up areas. And, even with standard commercial panels, the energy gains are dramatic. It is estimated that rooftop PV systems could generate almost 40% of electricity demands nationwide.

There’s no doubt that in both cases, a network of ‘productive rooftops’ could benefit the local community by supplying a portion of a necessary resource — either food or electricity — while also reducing their environmental burden. But is one better than the other?

This was the question posed by researchers from MIT and the University of Lisbon in a recent paper in the journal Cities. Focusing on the rooftops of a mixed-use neighborhood in Lisbon, they carried out a Cost-Benefit Analysis. Starting with existing data on everything from installation costs and resources used, to carbon footprint and yield, they modelled the impact that each installation would have on the local community over a period of 50 years.

And by looking at it that way, they concluded that for Lisbon, the use of rooftops for food production could yield significantly higher local value than solar PV energy generation. Of course, this is very site-specific. There is no one-size-fits-all solution to make cities more sustainable, and anyone who tells you otherwise is massively over-simplifying a complex issue. Now, all I hope is that some of those decision makers start using it.

1.According to the passage, green roofs don’t make a difference to ______.

A. medicine    B. agriculture

C. electricity    D. ecology

2.What does the underlined sentence mean in the last paragraph ?

A. Lisbon is the perfect targeted city for researchers.

B. In another city, the opposite conclusion can be drawn.

C. The conclusion about Lisbon can apply to all other cities.

D. It doesn’t make sense to install rooftop PV systems in Lisbon.

3.The author writes this article in order to ___________.

A. instruct decision makers what to do

B. inform us of the rise of urban rooftops

C. predict two fields where we can use rooftops

D. persuade us to make cities more sustainable

Answer

1. A

2. B

3. B

【解析】

本文是一篇说明文。这篇文章是告诉我们城市屋顶的兴起。

1.推理判断题。根据第二段中最后一句But when a rooftop offers access to sunlight, there are two more obvious candidates for its use - agriculture and solar power.可排除B；根据第六段最后一句It is estimated that rooftop PV systems could generate almost 40% of electricity demands nationwide.可排除C；根据第三段最后一句Green roofs can provide a habitat for birds and insects in an otherwise hostile environment.可排除D。根据这篇文章，文中未提到A项，可知绿色屋顶对医学没有影响。故选A。

2.句意猜测题。根据最后一段中Of course, this is very site-specific. There is no one-size-fits-all solution to make cities more sustainable, and anyone who tells you otherwise is massively over-simplifying a complex issue. Now, all I hope is that some of those decision makers start using it.“当然，这是非常位点专一的。要让城市更具可持续性，没有放之四海而皆适用的解决方案，任何不这么认为的人，都是在把一个复杂的问题过于简单化。现在，我只希望一些决策者开始使用它。”可推知划线句子的意思是“在另一个城市，可以得出相反的结论。”故选B。

3.主旨大意题。根据第一段Our cities have never been denser, taller, or busier than they are now, and with that, comes the constant battle for land. But if we look at aerial images of any city center, we can quickly spot plenty of unused space — the rooftops. 作者写这篇文章是为了告诉我们城市屋顶的兴起。故选B。