2022年雅思考试阅读模拟试题8含答案.pdf

天行健，君子以自强不息。地势坤，君子以厚德载物。——《易经》 雅思索试阅读模拟试题 (含答案) 1 There's 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 star's core. 2 Robert Ehrlich of George Mason University in Fairfax, Virginia, modelled the effect of temperaturefluctuations in the sun's interior. According to the standard view, the temperature of the sun's core is held constant by the opposing pressures of gravityand 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 , Grandpierre and a collaborator, Gábor ágoston,calculated that magnetic fields in the sun's core could produce small instabilities in the solar plasma. These instabilities would induce localised oscillations in temperature . 人不知而不愠，不亦君子乎？——《论语》 老当益壮，宁移白首之心；穷且益坚，不坠青云之志。——唐·王勃 4 Ehrlich's model shows that whilst most of these oscillations cancel each other out, somereinforce one another and become long-lived temperature variations. The favoured frequencies allow the sun's 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 sun's magnetic field could flip the fluctuations from one cycle length to the other. 5 These two timescales are instantly recognisable to anyone familiar with Earth's ice ages: for the past million years, ice ages have occurred roughly every 1