Question

【題目】 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】

這是一篇說明文。隨著新冠肺炎的爆發(fā)，新冠肺炎的癥狀與流感相似。文章主要說明了什么是病毒以及他們?yōu)楹螘�造成這么多麻煩。

【1】根據(jù)后文How can they cause so much trouble?可知他們怎么能制造這么多麻煩？由此可知，此處與后文同為設(shè)問句，提問“什么是病毒”，好引出后文對于病毒的解釋。故A選項(xiàng)“但是什么是病毒呢？”符合上下文語境，故選A。

【2】根據(jù)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——從植物和動物到最小的細(xì)菌。由此可知，上文是在說明為什么病毒對人類生命造成威脅的原因。故G選項(xiàng)“因此，它們總是有可能對人類的生命構(gòu)成威脅”符合上下文語境，故選G。

【3】根據(jù)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.可知病毒一直潛伏在我們周圍，等待宿主細(xì)胞的到來。它們可以通過鼻子、嘴巴、眼睛或皮膚上的傷口進(jìn)入我們的身體。由此可知，本句應(yīng)當(dāng)描述病毒進(jìn)入身體后的行為。其中上文中a host cell可對應(yīng)到C選項(xiàng)a host cell。故C選項(xiàng)“一旦進(jìn)入，它們就會試圖找到一個要感染的宿主細(xì)胞”符合上下文語境，故選C。

【4】根據(jù)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.”可知南非開普敦大學(xué)的病毒學(xué)家Ed Rybicki告訴《科學(xué)美國人》說:“追蹤病毒的起源是困難的，因?yàn)椴《静粫�留下化石，也因�(yàn)樗鼈冊谌肭值募?xì)胞內(nèi)復(fù)制自身的技巧�！庇纱丝芍�，病毒的起源目前還沒有明確的解釋。故E選項(xiàng)“到目前為止，對它們的起源還沒有明確的解釋”符合上下文語境，故選E。

【5】根據(jù)后文The technology and evidence we have today cannot be used to test these theories and identify the most plausible explanation.可知我們今天掌握的技術(shù)和證據(jù)不能用來檢驗(yàn)這些理論，也不能用來找出最合理的解釋。由此可知，目前這只是些理論，其中后文these theories可對應(yīng)到B選項(xiàng)中these are only theories。故B選項(xiàng)“目前，這些只是理論”符合上下文語境，故選B。