双壳类 shuāngkélèi bivalve Origin Definitions Defs Strokes Stroke Words Sentences Sents 双 雙 shuāng numeraladjective two Two; both; dual; twin; double; twofold壳 殼 ké noun shell The hard outer covering of something, such as an egg, nut, or crab; also refers to a casing, housing, or shell of a machine or device.类 類 lèi noun category kind; type; class; category; group