이렇게 세개 과거분사 맞나요?

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Earth Day is a celebration that began in America in 1970.

On that day, a U.S. politician called on the country’s people to protest against environmental pollution which leads to global warming.

  Earth Day is now celebrated by over a billion people in around 180 countries.

파란색부분!!

[익인1]

Begun 아냐?

[익인2]

그건 had begun

[글쓴이]

그럼 began은 그냥 과거인건가.......?

[익인3]

저거 중에 began은 그냥 과거