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TF阅读真题第770篇Economic Reasoning
Economics begins with the assumption that human actions are rational-intended for maximum self-benefit. For example, people pay more for a larger box of the same cer...
TF阅读真题第888篇The Origin of Mars’s Moons
The Origin of Mars's Moons Mars has two tiny moons, Phobos and Deimos. The orbits of both these satellites are nearly circular and close to the planet: Phobos orbits...
TF阅读真题第797篇The Australlan Megatauna Extinctions
The Australlan Megatauna Extinctions Many of the species of large animals(megafauna) such as mammoths, mastodons, ground sloths, and giant deer that roamed the Earth tens of thous...