β-barrelβ桶状结构barrel名词 n. [C]1.(中间粗两端细的)大桶The wine is left to mature in oak barrels. 葡萄酒在橡木桶中陈酿. a beer barrel 啤酒桶 2.一桶的量;(液量单位)桶[(+of)]This country produces ab...