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Put time-stamps at the beginning of each chapter, or time switch, and you should be okay. I'm not sure how you would indicate "present day" if your book starts "in the future," but that's up to you.
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#4: Attribution notice removed
Source: https://writers.stackexchange.com/a/18272 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#3: Attribution notice added
Source: https://writers.stackexchange.com/a/18272 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/