1 B1 カジュアル
公衆衛生上の対策や安全保護のために、顔にマスクをつけること。
"The sign at the hospital entrance told everyone to mask up before going inside."
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Mask up. It's not about your rights, it's about protecting other people.
— Joe Biden, public address on COVID-19 safety guidelines, 2020
分離不可