bun是可数名词。
bun
n.小圆甜蛋糕;小圆甜饼;圆面包;圆发髻
复数： buns
例句：
You cannot eat a bun in one bite.
你不能一口吃下一个面包。
She was sitting at the kitchen table eating a currant bun
她正坐在餐桌旁，吃着葡萄干圆面包。
Her hair was tied severely in a bun.
她的头发简单地盘成了一个发髻。
She wore her hair in a bun.
她盘了个发髻。
