雅思阅读实战训练模拟试题(八).docxVIP

智课网IELTS备考资料 雅思阅读实战训练模拟试题(八) 摘要： 为了帮助考生们更好地复习雅思考试，小马过河网雅思频道为各位考生整理了雅思阅读实战训练模拟试题(八)，供考生们参考使用，更多雅思阅读辅导请继续关注小马过河网雅思频道。  下面 小马 过河网 雅思 频道为大家整理了 雅思阅读 实战训练模拟试题(八)，供考生们参考，以下是详细内容。  ★Suns fickle heart may leave us cold  25 January 2007  From New Scientist Print Edition.  Stuart Clark  1.Theres a dimmer switch inside the sun that causes its brightness to rise and fall on timescales of around 100,000 years - exactly the same period as between ice ages on Earth.So says a physicist who has created a computer model of our stars core.  2.Robert Ehrlich of George Mason University in Fairfax, Virginia, modelled the effect of temperature fluctuations in the suns interior.According to the standard view, the temperature of the suns core is held constant by the opposing pressures of gravity and nuclear fusion.However, Ehrlich believed that slight variations should be possible.  3.He took as his starting point the work of Attila Grandpierre of the Konkoly Observatory of the Hungarian Academy of Sciences.In 2005, Grandpierre and a collaborator, Gábor ágoston, calculated that magnetic fields in the suns core could produce small instabilities in the solar plasma.These instabilities would induce localised oscillations in temperature.  4.Ehrlichs model shows that whilst most of these oscillations cancel each other out, some reinforce one another and become long-lived temperature variations.The favoured frequencies allow the suns core temperature to oscillate around its average temperature of 13.6 million kelvin in cycles lasting either 100,000 or 41,000 years.Ehrlich says that random interactions within the suns magnetic field could flip the fluctuations from one cycle length to the other.  5.These two timescales are instantly recognisable to anyone familiar with Earths ice ages: for the past million years, ice ages have occurred roughly every 100,000 years.Before that, they occurred roughly every 41,000 year