劍橋詞典from or referring to the period of time from about 2.5 million years ago to the present , in which modern humans appeared 第四紀(jì)的（迄今約250萬前至今的地質(zhì)時(shí)間段，這期間現(xiàn)代人出現(xiàn)） the Quaternary period 第四紀(jì) Quaternary glaciation 第四紀(jì)冰川化 the Quaternary noun [ 單數(shù)名詞 ] us Your browser doesn't support HTML5 audio the Quaternary period 第四紀(jì) 返回 Quaternary