Question

    Infections that cross over from other species are a deadly problem. The new coronavirus(冠状病毒) is the latest example of a disease that jumped from animals into humans. When infections do this, they can be deadly—and 2019-nCoV is no exception.

Nearly all viruses and bacteria that infect other organisms are completely harmless to people. But a tiny proportion can infect us and cause so-called zoonotic diseases, which come from animals rather than people. Such diseases are a massive problem. They make around 2.5 billion people ill every year and kill 2.7 million. Not all zoonotic diseases cause serious illness, but the Ebola virus, for example, currently kills most of those it infects.

One reason zoonotic viruses can be this deadly is that we lack pre-existing immunity( 免疫) to them. Another is that these viruses aren’t adapted to humans. Viruses that normally circulate among people can develop to become less deadly, as this helps them spread. “They don’t want you to drop dead within a day because you won’t pass it to anyone else,” says Chris Coleman at the University of Nottingham, UK.

To get infected, people need to come into contact with the animal the virus usually infects. This is most likely with domesticated animals. Camels carry the MERS coronavirus that causes sporadic human cases, for instance.

Many viruses that jump into people, like MERS, seldom spread from person to person. They can still infect thousands, though. Rabies is mostly passed on by dog bites, but kills 60,000 people a year. Others, such as Ebola, can spread from person to person, but aren’t very good at it and so cause relatively small outbreaks. The 2019 coronavirus, by contrast, appears quite good at spreading from person to person. We don’t know how deadly it is yet.

Biologists have been warning for decades about the risks of animal viruses spreading to people. There is good reason to worry. The last global pandemic(传染病), the 2009 flu that killed up to 400,000 people, was caused by a strain of flu that came from pigs. And that flu is thought to be a descendant of the 1918 flu, which came  from birds. HIV, which has infected about 75 million people, is now thought of as a human virus. But it jumped from chimpanzees into humans relatively recently, in the 1930s.

Coleman thinks there is little we can do to stop people coming into contact with animals that may carry dangerous viruses. “It’s very difficult to control that,” he says. Instead, he says we need to have vaccines( 疫苗) ready in advance. This could mean creating vaccines that are effective against a wide range of viruses and developing vaccines that require only minor changes to work against a new viral strain, much like annual flu vaccines.

1.What does the underlined word “circulate” in Para.3 probably mean?

A.Pass on. B.Attack each other.

C.Die away. D.Work together.

2.What can we learn from the passage?

A.People must keep away from wild animals.

B.The majority of viruses are a massive problem.

C.The 2009 flu had no connection with the 1918 flu.

D.Vaccines are an effective option to fight against viruses.

3.The passage mainly aims to _______.

A.analyze the origins of viruses

B.explain the consequence of diseases

C.draw people’s attention to zoonotic viruses

D.persuade people to protect the wild animals

4.Which of the following can be the best title for the passage?

A.How Are Vaccines Made?

B.Viruses Infected from Animals

C.A Global Health Emergency

D.Why Isn’t There a Coronavirus Vaccine Yet?

Answer

1.A

2.D

3.C

4.B

【解析】

本文是说明文。文章介绍了来自动物的人畜共患疾病致命的原因，并列举出历史上从动物传染给人类的一些病毒，以警告人们动物病毒传播给人类所带来的风险。

1.词义猜测题。根据划线词后的句子“…as this helps them spread. “They don’t want you to drop dead within a day because you won’t pass it to anyone else,”（ 因为这有助于它们的传播。 “它们（病毒）不希望你在一天之内就死掉，因为你不会把它传给其他人。）”，句中的spread和pass it to anyone else 意思为“传播”。因此可以推测，circulate意思为“传播”。故选A项。

2.细节理解题。根据文章最后一段中“he says we need to have vaccines( 疫苗) ready in advance. This could mean creating vaccines that are effective against a wide range of viruses and developing vaccines that require only minor changes to work against a new viral strain,（科尔曼认为我们需要疫苗提前做好准备。这可能意味着要研制能够有效对抗多种病毒的疫苗，以及开发只需稍加改变就能对付新病毒毒株的疫苗。）”可知，研发疫苗是对抗病毒的有效选择。故选D项。

3.推理判断题。文章第二段中“a tiny proportion can infect us and cause so-called zoonotic diseases,”说明了一小部分感染其他生物体的病毒和细菌会感染我们，引发人畜共患疾病；第三段中提到人畜共患疾病致命的原因“One reason zoonotic viruses can be this deadly is that we lack pre-existing immunity( 免疫) to them. Another is that these viruses aren’t adapted to humans.（人畜共患病毒可能致命的一个原因是我们缺乏预存免疫力。另一个原因是这些病毒不适应人类。）”；第六段提出生物学家一直在警告动物病毒传播给人类的风险。文章是关于人畜共患疾病的致命原因和风险。因此文章的目的是引起人们对人畜共患病毒的关注。故选C项。

4.主旨大意题。文章首句提出“Infections that cross over from other species are a deadly problem. （来自其他物种的感染是一个致命的问题）”。下文介绍了从动物到人类传染的疾病——人畜共患疾病的致命的原因，并且举出曾经发生过的动物传播给人类的病毒的例子。因此文章是关于从动物传播到人类的病毒，标题应该为“从动物感染的病毒”。故选B项。