寒假第四讲 六选四+阅读理解 讲义-2023-2024学年上海市高一上学期英语上外版（2020)必修第三册

高一英语·秋季 Lesson 4 Intensive Reading: Disaster prevention Intensive reading Disaster prevention 1六选四题型解读 Gap Filling: Sentence 难度：★★★★☆ 【语篇类型】议论文 【主题群】灾害防范 【来源】New Scientist A. But others warn that millions will die before we get there. B. That is based on an R number of somewhere between 2.5 and 3. C. By that estimate, some places have already achieved herd immunity. D. Our experience of other viruses show how herd immunity can develop. E. In other words, “no walls, barriers, cars or glass windows in the way”，says Tang. F. Only around 10 to 20 per cent of a population needs to be immune to the virus to achieve herd immunity. Can herd immunity ever happen The idea of herd immunity (群体免疫) has had a bumpy ride as the coronavirus pandemic has played out. It was initially touted① in some countries as a viable② strategy for dealing with the spread of COVID-19, before being dismissed. Today, some headlines celebrate the fact that many places might have achieved herd immunity including Britain and pockets of London, New York and Mumbai. _____1_____ The true picture is far messier, partly because scientists don't even agree on what herd immunity is, let alone how it might be achieved. So how will we know when populations are protected against the coronavirus? While the definition of herd immunity depends on who you ask, let's assume that it refers to a situation in which enough of a population is immune to a pathogen (病原体) that it no longer spreads throughout a community. Those who might be susceptible③ to it are indirectly protected thanks to the immune responses of others. These immune responses might have developed after a person was infected with a pathogen or after being vaccinated④ against it. _____2_____ Seasonal viruses like the common cold often sweep through a population until enough people have encountered them and built up a protective immune response for them to stop spreading. Widespread use of the MMR vaccine led to herd immunity for measles (麻疹) in