But the political risk that one or more countries decide to storm out of the single currency is rising all the time.

但是一个或多个国家决定冲出单一货币的政治危险一直在上升。

According to The Bread Guide, these holes are actually referred to as tunneling and can be caused by a multitude of reasons, such as not kneading the dough enough, being impatient with rising time, or using flour that's too dense.

按照《面包指南》的说法，这些洞实际上是“气孔通道”，造成这种现象的原因有很多，例如面团揉得不够均匀、醒发时间过长或使用的面粉密度过大。