面包bread为什么不可数

　　例句：

　　Breakfast consisted of dry bread and a cup of tea.

　　早餐有无黄油的面包和一杯茶。

　　The smell of new bread floated up from the kitchen.

　　厨房里飘出新鲜面包的香味。

　　I'm sorry, we've sold out of bread.

　　抱歉，我们的面包卖完了。

　　We had a simple meal of soup and bread.

　　我们喝汤，吃面包，凑合了一顿。