必需: essential; indispensable; vi ...保护比: protection ratio保护比: protection ratio; protective ratio保护比(射频): protection ratio (rf)声频保护比: audio frequency protection ratio讯号保护比: signal protection ratio音频保护比: af protection ratio同信道保护比: co-channel protection ratio上行线路保护比: up path protection ratio鸟类狩猎和保护比荷卢公约: benelux convention on the hunting and protection of birds需保养: need service必需: essential; indispensable; vitally need 发展工业所必需的原料 raw materials essential for industrial development; 用在最必需的地方 be used where it is most needed; 这些参考书是我们所必需的。 these reference books are necessary to us.; 必需品 necessities; consumer goods; necessaries; requirement不需保险: no insurance required不需保养的: maintenance free思想需保留: never show the bottom of your purse or your mind所需保单份数: policy and copies required必需的: essential; indispensable for/to; material; necessary; necessitous; obligate; required; requisite; vital必需费: necessary expenses必需酶: indispensable enzyme必需品: daily commodity; essential commodities; essential commodity; essential goods; estovers; indispensable; material; nece ity; necessaries; necessary wants; necessities; necessity goods; necessity n. something that is necessary; needments; requirements; requisite; want必需时: si op. sit; si opus sit必需项: entry required必需做: erfordern bentigen notwendig machen使必需: entail不需保养的地毯: coddle-free carpet