17．Vitamin B could help reduce the effects of the most dangerous type of air pollution，according to a new study published Monday．A team of international researchers looked at the damage caused by PM2.5，which has the most severe impact on health．
The team found that something as simple as taking vitamin B daily could greatly reduce the impact of the tiny particles（顆粒） on the human body，although they stressed that research was in its early stages and the sample（樣本） size was small．Once the particles are breathed in they can result in lung and systemic disease and stress，experts say．According to the WHO，92% of the world's population lives in places where the PM2.5 level is above the recommended level．However，how exactly these particles make people unwell is not fully understood．
For this study，published in the science journal PNAS，10 volunteers were initially exposed to clean air and given a placebo（安慰劑） to check their responses．The group then took another placebo for four weeks before being exposed to heavily polluted air from downtown Toronto，where thousands of cars pass every hour．The bad air was given to the volunteers through an"oxygen type"face mask．The experiment was then repeated，with each volunteer taking vitamin B daily--made up of 2.5mg of folic acid，50mg of vitamin B6，and 1mg of vitamin B12．B6 can be found in liver，chicken and nuts； and B12 in fish，meat，eggs，milk and some cereals．The researchers found that four weeks of B vitamin supplements reduced the damage of PM2.5 exposure by 28-76%．The results highlight how prevention at an individual level could be used to fight the harmful effects of PM2.5，the researchers said．
Future studies，especially in heavily polluted areas，are urgently needed to prove our findings and finally develop preventive methods using B vitamins to contain the health effects of air pollution，said one researcher．
28．According to this passage，how does PM2.5 do harm to our health？A
A．The particles can cause stress and lung disease as well．
B．The particles can lead to lung disease and heart attack．
C．The particles can cause blood disease and eye disease．
D．The particles can lead to heart attack and emotional diseases．
29．What can we learn from this passage？D
A．Vitamin C can help reduce the bad impact of PM2.5．
B．PM2.5is actually not as dangerous as people expect．
C．The scientists know why the vitamin can help fight PM2.5．
D．More than half of the world's population suffer from PM2.5．
30．Which food below can B12 be found in？A
A．Eggs．
B．Nuts．
C．Liver．
D．Apples．
31．What does the underlined word"highlight"in the third paragraph mean？A
A．To emphasize．
B．To weigh．
C．To represent．
D．To explain．
分析 短文主要介紹了維生素B族可減輕PM2.5造成的健康損傷．
解答 28．A，細(xì)節(jié)理解題，根據(jù)句子Once the particles are breathed in they can result in lung and systemic disease and stress可知，PM2.5會(huì)引起壓力和肺疾病，故答案為A．
29．D，細(xì)節(jié)理解題，根據(jù)句子92% of the world's population lives in places where the PM2.5 level is above the recommended level可知，超過一半的人遭受PM2.5帶來的傷害，故答案為D．
30．A，細(xì)節(jié)理解題，根據(jù)句子B12 in fish，meat，eggs，milk and some cereals可知，雞蛋里含有B12，故答案為A．
31．A，詞義猜測題，前文提到The researchers found that four weeks of B vitamin supplements reduced the damage of PM2.5 exposure by 28-76%，服用維生素B四個(gè)星期會(huì)降低28-76%PM2.5造成的傷害，可知這個(gè)結(jié)果是要強(qiáng)調(diào)維生素B的保護(hù)作用，故答案為A．
點(diǎn)評 解答任務(wù)型閱讀理解題，首先對原文材料迅速瀏覽，掌握全文的主旨大意．因?yàn)殚喿x理解題一般沒有標(biāo)題，所以，速讀全文，抓住中心主旨很有必要，在速讀的過程中，應(yīng)盡可能多地捕獲信息材料．其次，細(xì)讀題材，各個(gè)擊破．掌握全文的大意之后，細(xì)細(xì)閱讀每篇材料后的問題，弄清每題要求后，帶著問題，再回到原文中去尋找、捕獲有關(guān)信息．最后，要善于抓住每段的主題句，閱讀時(shí)，要有較強(qiáng)的針對性．對于捕獲到的信息，要做認(rèn)真分析，仔細(xì)推敲，理解透徹，只有這樣，針對題目要求，才能做到穩(wěn)、準(zhǔn)．
