【托福阅读题型：Volcanic Islands修辞目的题】托福阅读中句子插入题是重要题型之一。根据托福阅读题型不同来进行专项练习，是短期提高托福阅读能力的有效方法。同学们需要多加练习哦!

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　　托福阅读修辞目的题：Volcanic Islands

　　【Paragraph 1】Earth’s surface is not made up of a single sheet of rock that forms a crust but rather a number of　“tectonic plates” that fit closely, like the pieces of a gain jigsaw puzzle. Some plates carry islands or continents, others　form the seafloor. All are slowly moving because the plates float on a denser sem-iliquid mantle, the layer between the　crust and Earth’s core. The plates have edges that are spreading ridges (where two plates are moving apart and new　seafloor is being create○, subduction zones (where two plates collide and one plunges beneath the other), or transform　faults (where two plates neither converge nor diverge but merely move past one another). It is at the boundaries between　plates that most of Earth’s volcanism and earthquake activity occur.(The Formation of Volcanic Islands)

　　The author mentions “spreading ridges”, “subduction zones”, and “transform faults” in order to

　　○ illustrate that the boundaries of tectonic plates are neat, thin lines

　　○ explain why some tectonic plates carry islands or continents while others form the seafloor

　　○ explain the complex nature of the edges of tectonic plates

　　○ provide examples of areas of tectonic plates where little geologic action occurs

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