(练习)课时分层作业9 Unit 9 Human READING & WRITING-【提分教练】2023-2024学年新教材高中英语选择性必修第三册(北师大版2019)

课时分层作业(九) Ⅰ．阅读理解 A People who have kids live longer than those who remain childless，an academic study has suggested．Researchers believe it is because adults' immune systems are “refreshed” when kids go to nursery and start picking up infections． During the course of someone's life，their immune system can become weaker．But when kids start bringing infections home，their parents' immune systems get a workout．Non­parents—unless they are teachers or nurses—perhaps do not get the same exposure to infection． Writing in the journal Scientific Reports，Miguel Portela said parents had less risk of dying from infection than non­parents and if they did，it was about five years later．He said, “A parent's immune system is refreshed by a child's infections at a time when their own protection starts wearing thin．” He added．“With this improved immune system，the parent has a better chance to defend whatever infections that might strike when old and weak and parenthood is rewarded in individual terms through an improved immunization against infections．” Naturally there are other reasons why some people live longer than others，but they may not be comparable with becoming a parent．The academics say that high income and house ownership are always associated with higher survival but less so than having children． Mr．Portela admits the research is far from complete，saying that while the results “record a relationship between the presence of children and death rate，the specific transmission mechanisms remain unclear”．He acknowledges the presence of other，perhaps behavioral factors in parents which result in changed death rate compared to individuals without children．He adds，“While the relationships of lifestyle choices such as smoking，obesity，drinking and other behavioral factors with life expectancy and causes of death are well studied and understood，the same cannot be said for the individual decision to become a parent．” 【语篇解读】　本文是一篇说明文。一项学术研究表明，有孩子的人比没有孩子的人寿命更长。研究人员认为，这是因为当孩子们去托儿所并开始感染病毒时