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Explore Wonders | Find: 消防工程师考试网（网址:qmh8.com）消防工程师考试网_消防工程师考试网_消防工程师考试网_Xs7X7YpF | Wonderopolis

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What Is a Spit Valve?

We don’t mean to toot our own horn, but we think today’s Wonder of the Day will be music to your ears.

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What Is a Spit Valve?
Who Is Uncle Sam?

Today’s Wonder of the Day features everyone’s favorite uncle!

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Who Is Uncle Sam?
How Do Mood Rings Work?

We hope you’re in the mood for an interesting Wonder of the Day today!

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How Do Mood Rings Work?