备用二级头呼吸器bèi yòng èr jí tóu hū xī qìbeiyongerjitouhuxiqi(scuba diving) backup regulator; octopusCharacters in this word二two吸to inhale, to suck in呼to breathe, to exhale, to sigh器device, instrument, tool备to prepare头head用to use, to employ, to apply级level, rankStudy it in Yanamino