![Belowisaselectionfromapopularsciencebook.Ifbloodisred，w...]( "Belowisaselectionfromapopularsciencebook.Ifbloodisred，w...")
- 问题详情：Belowisaselectionfromapopularsciencebook.Ifbloodisred，whyareveins(静脉)blue?Actually，veinsarenotblueataremoreofaclear，yellowishoughbloodlooksredwhenit'soutsidethebody，whenit'ssittinginaveinnearthesurfaceoftheskin，it'smoreofadarkreddishpurplethe...
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