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  3. Allergy has become more and more common over the last 30 years. It is a reaction that occurs when the immune system has a strang

Allergy has become more and more common over the last 30 years. It is a reaction that occurs when the immune system has a strang

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问题
   Allergy has become more and more common over the last 30 years. It is a reaction that occurs when the immune system has a strange and unnecessary reaction to a substance which is normally harmless, such as pollen (花粉)or peanuts. The immune system is there to protect the body against outside attackers, including viruses, bacteria and parasites. To defend your body against an attacker, the immune system remembers these dangerous micro-organisms and attacks them if it meets them again. This work is done by antibodies. The immune system in allergy sufferers makes antibodies against harmless substances, because it mistakenly believes them to be dangerous.
   【B1】______ Sometimes people can eat nuts for years and then suddenly become allergic to them. What has happened is that the immune system has now decided the substance is dangerous and has made an allergy antibody. This antibody then attaches itself to cells, which contain histamine (组织胺). When the antibodies meet the allergen the next time, they attempt to destroy it. As they do that, the surface of the cells is broken, and histamine is released. The histamine and other chemicals inflame the tissues. This leads to the symptoms of allergy, such as swelling, rashes, sneezing and breathlessness.
   【B2】______Some people are bom with the ability to make lots of allergy antibodies,  and they are more likely to develop allergies and allergic disorders such as hay fever and asthma.
   【B3】______ We eat more processed foods, with a wide range of additives and colourings; more and more people have central heating and double glazing, making our houses warmer and less draughty.

   【B4】______At one time our immune systems were kept busy fighting off disease and trying to win the battle for health, but, antibiotics have reduced the amount of work our immune systems have to do. Now experts think they may direct spare energy to harmless substances. In other words, our immune systems have become oversensitive.
   【B5】______ Sufferers may be given medicine to control symptoms, and they may also be offered tests to find out what substances trigger an allergic reaction so that they can avoid contact with these substances in future.
Questions 61-65
Complete the passage with the following sentences. There are two extra sentences that you do not need to use.
A. There may also be a link between allergies and antibiotics.
B. Allergies run in families.
C. A good deal of research is being devoted to finding a cure for allergies.
D. One-third of us are affected by allergy at some point in our lives.
E. Experts believe more people have developed allergies because of changes in our lifestyle which have exposed us to more allergens.
F. In the UK, five per cent of children suffer from food allergy.
G. An allergic reaction may not happen the first time a sufferer meets an allergen.
【B1】
选项
答案G
解析 该空后面提到“有时人们可以吃几年的坚果，然后突然对它们过敏”。由此可知，该空应该与人们遇到过敏原时并不会立刻产生过敏反应有关，符合条件的只有G项(过敏反应可能不会在患者第一次遇到过敏原时发生。)
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