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TPO对于我们的托福备考非常有用，大家还在苦于找不到资料吗？下面小编给大家带来托福TPO8阅读真题文本及参考答案Part3，希望可以帮助到你们。

托福TPO8阅读真题文本Part3

Running Water on Mars

Photographic evidence suggests that liquid water once existed in great quantity on the surface of Mars. Two types of flow features are seen: runoff channels and outflow channels. Runoff channels are found in the southern highlands. These flow features are extensive systems-sometimes hundreds of kilometers in total length-of interconnecting, twisting channels that seem to merge into larger, wider channels. They bear a strong resemblance to river systems on Earth, and geologists think that they are dried-up beds of long-gone rivers that once carried rainfall on Mars from the mountains down into the valleys. Runoff channels on Mars speak of a time 4 billion years ago (the age of the Martian highlands), when the atmosphere was thicker, the surface warmer, and liquid water widespread.

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