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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Precambrian cratons -- some of Earth's oldest rocks -- were uninhabitable for microbes for much of their existence, with the longest period of habitability not much beyond a billion years, and many only for the past 50 million to 300 million years, according to a paper correlating Earth's deep biosphere with geologic history.

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