All visitors to the site must wear safety helmet.

到工地的所有参观者必须带上安全帽。

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All participants must wear a safety helmet or bike helmet during the race.

所有参赛者必须佩戴安全帽或单车头盔进行比赛。

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All participants must wear a safety helmet or bike helmet during the race.

所有参赛者必须佩戴安全帽或单车头盔进行比赛。

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