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。