Question

    From talking robots and video phones to rovers （探测器）on Mars, technology has become so advanced that the previously impossible seems to occur on a daily basis. And yet—we still have no cure for the common cold.

Why can't we stop the common cold? According to Peter Barlow, a scientist at Edinburgh Napier University in the UK, the main challenge lies in the many different types of cold viruses that are produced by the rhinoviruses （鼻病毒），Scientific American reported. There are at least 160 types. They mutate so easily that they quickly become resistant to drugs, or learn to hide from our immune systems. In other words, a single cure isn't likely to work on every type of cold.

However, researchers from Stanford University and the University of California, San Francisco, have found a possible answer. They discovered a protein that the viruses need. Without it, they can't spread inside your body.

To identify the gene which produces the specific protein needed by the viruses, researchers used a gene-editing technique to test all genes in the human genome（基因组）one by one for thousands of cell.

These modified （改变的）cells were then exposed to a range of enteroviruses （肠道病毒）， including the rhinoviruses which cause the common cold.

All the viruses were unable to replicate（复制）inside cells without a gene that produces a specific protein, called methyltransferase（甲基转移酶）SETD3.

Then, they tested genetically（从基因方面）modified mice, which were completely unable to produce the protein. The mice were able to live healthy, normal lives without the protein.

"Lacking that gene protected the mice completely from viral （病毒的）infection,” associate professor Jan Carette, from Stanford, told the BBC.

"These mice would always die, but they survived and we saw a very strong reduction in viral replication and very strong protection."

Carette said the plan is to find a drug which can temporarily suppress（抑制） the protein, instead of producing genetically modified humans.

“We have identified a fantastic target that all enteroviruses and rhinoviruses require and depend on. Take that away and the virus really has no chance," said Carette.

"This is a really good first step—the second step is to have a chemical that mimics（模拟） this genetic deletion,” he added.

1.What does the underlined word "mutate” mean in English?

A.To change a new form.

B.To identify a new gene.

C.To check a modified cell.

D.To cure a viral infection.

2.What is the article mainly about?

A.Why it is so hard to cure the common cold.

B.The possible link between rhinoviruses and the common cold.

C.A possible way to stop viral infections that cause the common cold.

D.The functions of a protein needed by viruses.

3.What does Peter Barlow think is the main problem for prevention of the common cold?

A.The slow mutation of some genes.

B.The fast speed at which rhinoviruses spread.

C.The harm rhinoviruses do to the immune system.

D.The wide variety of cold viruses created by rhinoviruses.

4.What can we learn about the protein needed by the viruses?

A.It helps the viruses replicate inside our bodies.

B.It allows the viruses to change easily.

C.It helps the viruses become resistant to drugs.

D.It increases the spread of the viruses.

5.What did the researchers discover in their gene-editing study?

A.Genetically modified mice died because they lacked the protein.

B.The modified cells seemed to protect the mice against viral infections.

C.More methyltransferase SETD3 was produced after the cells were modified.

D.The gene-editing technique was more effective against enteroviruses than rhinoviruses.

6.What do the researchers plan to do next, according to Carette?

A.Conduct experiments on genetically modified humans.

B.Identify a drug that can help reduce the protein.

C.Apply this gene-editing technique to control other viruses.

D.Find a chemical that can cure all enteroviruses and rhinoviruses.

Answer

1.A

2.C

3.D

4.A

5.B

6.B

【解析】

本文是一篇说明文，介绍了斯坦福大学和旧金山加州大学的研究人员找到了一种可能阻止引起人们感染感冒病毒的方法——抑制一种叫做甲基转移酶SETD3的蛋白质，因为这种蛋白质能够帮助感冒病毒在我们体内复制。

1.词义猜测题。根据画线词后的“they quickly become resistant to drugs, or learn to hide from our immune systems.”可知，它们很快就会对药物产生抗药性，或者学会躲过我们的免疫系统，这说明这些病毒很容易变异，由此可知画线词词义为“变异（变成一种新类型的病毒）”，故A项正确。

2.

3.

4.推理判断题。根据第六段中的“All the viruses were unable to replicate（复制）inside cells without a gene that produces a specific protein, called methyltransferase（甲基转移酶）SETD3.”可知，所有的病毒都不能在细胞内复制，因为它们没有一种基因，这种基因可以产生一种叫做甲基转移酶SETD3的蛋白质，由此可知，病毒所需的蛋白质能够帮助病毒在我们体内复制，故A项正确。

5.

6.推理判断题。根据最后一段“"This is a really good first step—the second step is to have a chemical that mimics（模拟） this genetic deletion,” he added.”可知，“这是一个很好的第一步，第二步是让一种化学物质模拟这种基因缺失”，他（卡雷特）补充说，由此可知，卡雷特认为研究人员下一步打算找出一种能帮助减少这种蛋白质的药物，故B项正确。