Question

【题目】 Following the outbreak of the novel coronavirus pneumonia (NCP), also named COVID -19 by WHO, there is a general fear of the unknown virus as its full effects remain to be seen. Fever, coughing, sore throat, difficulty breathing – the NCP’s symptoms are similar to the common cold or the flu, but it’s potentially more dangerous.

Viruses could be deadly, like HIV and Ebola. 【1】 How can they cause so much trouble?

Viruses are non-living organisms approximately one-millionth of an inch long. Unlike human cells or bacteria, they can’t reproduce on their own. Instead, they invade the cells of living organisms to reproduce, spread and take over.

Viruses can infect every living thing – from plants and animals down to the smallest bacteria. 【2】 Sometimes a virus can cause a disease so serious that it is fatal. Other viral infections bring about no noticeable reaction.

Viruses lie around our environment all of the time, waiting for a host cell to come along. They can enter our bodies by the nose, mouth, eyes or breaks in the skin. 【3】 For example, HIV, which causes AIDS, attacks the T-cells of the immune system.

But the basic question is, where did viruses first come from? 【4】 “Tracing the origins of viruses is difficult,” Ed Rybicki, a virologist at the University of Cape Town in South Africa, told Scientific American, “because viruses don’t leave fossils (化石) and because of the tricks they use to make copies of themselves within the cells they’ve invaded.”

However, there are three main theories to explain the origin of viruses. First, viruses started as independent organisms, then became parasites (寄生者). Second, viruses evolved from pieces of DNA or RNA that “escaped” from larger organisms. Third, viruses co-evolved with their host cells, which means they existed alongside these cells.

【5】 The technology and evidence we have today cannot be used to test these theories and identify the most plausible explanation. Continuing studies may provide us with clearer answers.

A.But what are viruses?

B.For the time being, these are only theories.

C.Once inside, they try to find a host cell to infect.

D.The answer may be even less satisfactory than it now appears.

E.Until now, no clear explanation for their origin exists.

F.Experts are concerned about the bad effect that it had on people’s health.

G.For this reason, they always have the potential to be dangerous to human life.

Answer 1

【答案】

【1】A

【2】G

【3】C

【4】E

【5】B

【解析】

这是一篇说明文。随着新冠肺炎的爆发，新冠肺炎的症状与流感相似。文章主要说明了什么是病毒以及他们为何会造成这么多麻烦。

【1】根据后文How can they cause so much trouble?可知他们怎么能制造这么多麻烦？由此可知，此处与后文同为设问句，提问“什么是病毒”，好引出后文对于病毒的解释。故A选项“但是什么是病毒呢？”符合上下文语境，故选A。

【2】根据上文Viruses can infect every living thing – from plants and animals down to the smallest bacteria.可知病毒可以感染一切生物——从植物和动物到最小的细菌。由此可知，上文是在说明为什么病毒对人类生命造成威胁的原因。故G选项“因此，它们总是有可能对人类的生命构成威胁”符合上下文语境，故选G。

【3】根据上文Viruses lie around our environment all of the time, waiting for a host cell to come along. They can enter our bodies by the nose, mouth, eyes or breaks in the skin.可知病毒一直潜伏在我们周围，等待宿主细胞的到来。它们可以通过鼻子、嘴巴、眼睛或皮肤上的伤口进入我们的身体。由此可知，本句应当描述病毒进入身体后的行为。其中上文中a host cell可对应到C选项a host cell。故C选项“一旦进入，它们就会试图找到一个要感染的宿主细胞”符合上下文语境，故选C。

【4】根据后文“Tracing the origins of viruses is difficult,” Ed Rybicki, a virologist at the University of Cape Town in South Africa, told Scientific American, “because viruses don’t leave fossils and because of the tricks they use to make copies of themselves within the cells they’ve invaded.”可知南非开普敦大学的病毒学家Ed Rybicki告诉《科学美国人》说:“追踪病毒的起源是困难的，因为病毒不会留下化石，也因为它们在入侵的细胞内复制自身的技巧。”由此可知，病毒的起源目前还没有明确的解释。故E选项“到目前为止，对它们的起源还没有明确的解释”符合上下文语境，故选E。

【5】根据后文The technology and evidence we have today cannot be used to test these theories and identify the most plausible explanation.可知我们今天掌握的技术和证据不能用来检验这些理论，也不能用来找出最合理的解释。由此可知，目前这只是些理论，其中后文these theories可对应到B选项中these are only theories。故B选项“目前，这些只是理论”符合上下文语境，故选B。