题目

阅读理解 A recent study published in the journal Nature has revealed that our Medieval ancestors left us with a biological legacy: Genes that may have helped them survive the Black Death make us more vulnerable to certain diseases today. Barreiro and his colleagues examined ancient DNA samples from the bones of more than 200 people from London and Denmark who died over about 100 years that stretched before, during, and after the Black Death swept through that region. They identified four genes that, depending on the variant, either protected against or increased vulnerability(易损性)to the bacteria that causes bubonic plague(腺鼠疫). They found that what helped people in Medieval times led to problems generations later — raising the frequency of mutations(突变) harmful in modern times. Some of the same genetic variants identified as protective against the plague are associated with certain autoimmune disorders, such as Crohn's disease. In these sorts of diseases, the immune system that defends the body against disease and infection attacks the body's own healthy tissues. Past research has also sought to examine how the Black Death affected the human genome. But Barreiro said he believes theirs is the first demonstration that the Black Death was important to the evolution of the human immune system. One unique aspect of the study, he said, was to focus on a narrow time window around the event. It's extremely sophisticated and addresses important issues, such as how the same version of a gene can protect people from a horrific infection and also put modern people at risk for other illnesses. All of this begs the question: Will the COVID-19 pandemic have a big impact on human evolution? Barreiro said he doesn't think so because the death rate is so much lower and the majority of people who have died had already had children. In the future, however, he said more deadly pandemics may well continue to shape us at the most basic level. "It's not going to stop. It's going to keep going for sure. " （1） How did Barreiro's team come up with the finding? A . By analyzing DNA samples from targeted bones. B . By testing the vulnerability of four specific genes. C . By identifying the frequency of harmful mutations. D . By focusing on the consequences of autoimmune disorders. （2） What does Barreiro believe make their research distinct from previous research? A . It is the first to show a variant of gene can lead to infection. B . It illustrates how gene variants can make us free of immune disorders. C . It focuses on an extensive time window around the Black Death event. D . It is the first to confirm the plague is responsible for certain immune disorders. （3） Which of the following statements will Barreiro probably agree with? A . There will be more pandemics causing death to people. B . COVID-19 pandemic will continue to impact human evolution. C . New pandemics may still influence how human immune system develops. D . Modern people are protected from deadly pandemics due to the same gene. （4） What is a suitable title for the text? A . Genetic variants: They make us victims of the Black Death B . Genetic twist: Medieval plague may have shaped our immunity C . Time window: The factor plays an important role in a recent study D . Deadly pandemics: They will keep changing our immune system for sure 答案： A D C B

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