Most rocks are made of minerals containing silicon and oxygen, the most abundant elements in the Earth ’ s crust. There are three kinds of rock : igneous, sedimentary and metamorphic. Igneous rocks form when molten rock cools and solidifies. Sedimentary rocks originate when particles settle out of water or air. Metamorphic rocks result when existing rocks are changed by heat or pressure.
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.