Question

【题目】B vitamins（维生素）may offer some protection against the effect of air pollution,a new study suggests.

The scientists say the effect is real but stress the limitations of their work.Follow-up studies are urgently needed, they say,in heavily polluted cities like Mexico.

According to the World Health Organization (WHO),over 90% of the world's population live in heavily-polluted areas.The one of the pollutants that is considered the most dangerous is very fine particulate matter, referred to as PM2.5.At around 1/30 the width of a human hair,PM2.5 can go deep into the human lung and contribute to lung and heart health problems in the young and old.

Scientists have long suspected that PM2.5 causes what are termed epigenetic（表观遗传）changes in our cells that can damage our health.Now in this new human trial,an international team of scientists wanted to see if exposure to concentrations of PM2.5 could be mitigated by daily B vitamins.

Ten volunteers were tested initially exposed to clean air and their basic responses were measured.The same volunteers were later tested with large doses（剂量）of B vitamins while exposed to air containing high levels of PM2.5.The researchers found that a four-week B vitamin intake limited the PM2.5 effect by between 28-76% at ten gene locations.They found a similar reduction in effect on the mitochondrial DNA,the parts of cells that produce energy.

However,the researchers caution that their study,while observing a real effect,has limitations.As well as the small number of participants,there was little information on the size of the B vitamin dose that caused the response.

【1】What is the main idea of the text?

A. B vitamins may fight against PM2.5.

B. PM2.5 can lead to epigenetic changes.

C. Further studies should be done on PM2.5.

D. Exposure to PM2.5 is more and more serious.

【2】Which can replace the underlined word "mitigated" in Paragraph 4?

A. measured B. ignored

C. reduced D. observed

【3】How many limitations does the text mention about the new study?

A. 2. B. 3.

C. 4. D. 5.

【4】How does the writer of the text like the new study?

A. He believes it deeply. B. He criticizes it strongly.

C. He thinks it needs testing again. D. He shows no opinion about it.

Answer 1

【答案】

【1】A

【2】C

【3】A

【4】D

【解析】一项研究表明，维生素B有助于帮助人体抵抗PM2.5。虽然后续研究还有待更进，但科学家已经肯定了维生素B在抵抗PM2.5方面的作用。

【1】主旨大意题。通读全文可知这篇文章的主题句是B vitamins（维生素）may offer some protection against the effect of air pollution,a new study suggests.故选A。

【2】词意猜测题。根据语境an international team of scientists wanted to see if exposure to concentrations of PM2.5 could be mitigated by daily B vitamins科学家想知道暴露在PM2.5之下，维生素B是否会减少接触的浓度。文章第一段就说明了维生素B有助于人体抵抗PM2.5，所以这里的研究目的是想知道维生素B是否会减少PM2.5浓度。故选C。

【3】细节题。根据文章最后一段As well as the small number of participants,there was little information on the size of the B vitamin dose that caused the response.可知，维生素B在抵抗PM2.5的研究局限性有两方面，一是参与实验的人数太少，二是关于产生效果维生素B的量的相关信息太少。故选A。

【4】态度观点题。通读全文可知，作者只是描述了一项科学研究，向读者介绍PM2.5及维生素B帮助人体抵抗PM2.5的研究过程，并没有表现出自己的观点。故选D。