阅读必备：托福考试阅读长难句汇总9

>>2019年托福考试：阅读必备：托福考试阅读长难句汇总9

>>托福保分精品课程

1. Moreover, recent research on obsidian tools found at Olmecs sites has shown that some of the obsidian obtained by the Olmecs originated near Teotihuacán.

2. The growing power of the elite, who controlled the economy, would give them the means to physically coerce people to move to Teotihuacán and serve as additions to the labor force.

3. By measuring how many of these meteorites fall to Earth over a given period of time, scientists can estimate how long it might have taken to deposit the observed amount of lr in the boundary clay.

4. 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.

5. 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.

6. The onrushing water arising from these flash floods likely also formed the odd teardrop-shaped “islands” (resembling the miniature versions seen in the wet sand of our beaches at low tide) that have been found on the plains close to the ends of the outflow channels.

7. Judging from the width and depth of the channels, the flow rates must have been truly enormous―perhaps as much as a hundred times greater than the 105 tons per second carried by the great Amazon river.

8. A computer-generated view of the Martian north polar region shows the extent of what may have been an ancient ocean covering much of the northern lowlands.

9. Proponents point to features such as the terraced “beaches” shown in one image, which could conceivably have been left behind as a lake or ocean evaporated and the shoreline receded.

10. But detractors maintain that the terraces could also have been created by geological activity, perhaps related to the geologic forces that depressed the Northern Hemisphere far below the level of the south, in which case they have nothing whatever to do with Martian water.

这就是小编整理相关的托福考试素材了，大家一定要仔细分析，要理解记忆这样才能灵活掌握知识点，这篇文章只是坦途网托福考试频道其中的篇，还有很多的素材和试题等着大家去学习，快点点击进去看看吧！