Questions 46 to 50 are based on the following passage.
【真题来源：2020年9月大学英语四级真题（第二套）Part Ⅲ，Section C，第46-50题】
Passage One
When is cleaning walls a crime? When you're doing it to create art, obviously. A number of street artists around the world have started expressing themselves through a practice known as reverse graffiti （涂鸦）. They find dirty surfaces and paint them with images or messages using cleaning brushes or pressure hoses （高压水管）. Either way, it's the same principle: the image is made by cleaning away the dirt. Each artist has their own individual style but all artists share a common aim: to draw attention to the pollution in our cities. The UK's Paul Curtis, better known as Moose, operates around Leeds and London and has been commissioned by a number of companies to make reverse graffiti advertisements.
Brazilian artist, Alexandre Orion, turned one of Sao Paulo's transport tunnels into an amazing wall painting in 2006 by getting rid of the dirt. Made up of a series of white skulls （颅骨），the painting reminds drivers of the effect their pollution is having on the planet. "Every motorist sits in the comfort of their car, but they don't give any consideration to the price their comfort has for the environment and consequently for themselves," says Orion.
The anti-pollution message of the reverse graffiti artists confuses city authorities since the main argument against graffiti is that it spoils the appearance of both types of property: public and private. This was what Leeds City Council said about Moose's work: "Leeds residents want to live in clean and attractive neighbourhoods. We view this kind of advertising as environmental damage and will take strong action against it." Moose was ordered to "clean up his act." How was he supposed to do this: by making all property he had cleaned dirty again?
As for the Brazilian artist's work, the authorities were annoyed but could find nothing to charge him with. They had no other option but to clean the tunnel but only the parts Alexandre had already cleaned. The artist merely continued his campaign on the other side. The city officials then decided to take drastic action. They not only cleaned the whole tunnel but every tunnel in Sao Paulo.
What do we learn from the passage about reverse graffiti?
根据题干关键词reverse graffiti定位至首段。该段第三句中提到了reverise graffiti，接下来的第四五句具体介绍了这种艺术是用清洁刷或高压水管在满是污垢的墙面作画或写标语，即通过清除污垢画上图像。故答案选D项。文中说的是通过清洁刷或高压水管清除污垢来作画，而不是用颜料，故排除A项；文章首段倒数第二句提到，但是所有艺术家都有一个共同的目的：提醒人们注意我们城市里的污染，而非给当地居民造成困扰，故排除B项；C项在文中并未提及，故排除。
What do reverse graffiti artists try to do?
根据题干关键词reverse graffiti artists定位至首段倒数第二句。该句提到，所有艺术家都有一个共同的目的：提醒人们注意我们城市里的污染。故答案选C项。A项和D项在文中均未提及，故排除；反向涂鸦虽然产生了“美化城市环境”的效果，但这并非反向涂鸦艺术家的目的，故排除B项。
What do we learn about Brazilian artist Alexandre Orion?
根据题干关键词Brazilian artist Alexandre Orion定位至第二段。该段首句提到，这位艺术家用清除灰尘的方法把圣保罗的一条交通隧道变成了一幅令人惊叹的壁画。说明，选择反向涂鸦创作的场所是“交通隧道”(transport tunnels)，故答案选B项。white skulls出现在第二段第二句中，该句提到，他在隧道创作的壁画内容是一系列白色颅骨，但其创作的目的是提醒司机汽车给环境造成的污染，不能推断出“他擅长画白色颅骨”，故排除A项；C项中的 banning在文中并未提及，故排除；文章中只提到奥里恩创作了一幅令人惊叹的反向涂鸦壁画，但不能推断出“他喜欢创作艺术作品”，D项属过度推断，故排除。
What does the author imply about Leeds City Council's decision?
根据题干关键词Leeds City Council's decision定位至第三段。该段中提到，利兹市议会这样评价穆斯的作品：“利兹市居民想要生活在干净和有魅力的社区里。我们认为这类广告是对环境的破坏，我们将采取强硬措施来抵制它。”穆斯被要求“清理自己做过的事”。他应该怎么做呢？要把他已经清洗干净的所有墙面再弄脏吗？作者以反讽的语气说明无法清除已经创作好的反向涂鸦作品，可推断出作者认为利兹市议会的决定很荒唐，故答案选A项。同时排除B项和D项；C项在文中找不到相关依据，故排除。
How did Sao Paulo city officials handle Alexandre Orion's reverse graffiti?
根据题干关键词city officials定位至末段。该段结尾处提到，圣保罗市官员决定采取严厉措施。他们不仅清理了整个隧道，而且把圣保罗的每一条隧道也都一并清理了。可知，所有隧道被清理干净了，亚历山大就无法在隧道里进行反向涂鸦创作了，故答案选D项。文中并未提及让亚历山大去清理隧道，故排除A项；B项中的 ban在文中并未提及，故排除；C项与末段首句中提到的，当局很恼火，却苦于找不到任何理由指控他所表述的意思相悖，故排除。