前寒武纪 qiánhánwǔjì Precambrian Definitions Defs Origin Strokes Stroke Words Sentences Sents 前寒武纪 前寒武紀 qiánhánwǔjì Precambrian the geological period before approximately 540 million years ago
前寒武纪 前寒武紀 qiánhánwǔjì Precambrian the geological period before approximately 540 million years ago