Research indicates that over billions of years, surface water has been transported deep into the Earth by descending, or subducted, tectonic plates. Upon reaching the core-mantle boundary, about 1, 800 miles below the surface, this water triggers a profound chemical interaction, altering the core's structure.
PTELook at the text below. In 35 seconds, you must read this text aloud as naturally and clearly as possible. You have 35 seconds to read aloud.
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Beginning in 35 seconds.