The vacuum flask has a strong casing, which won't crack or chip.这个真空瓶有一个坚固的外壳,不会破裂。
When most people think of the word "education", they think of a pupil as a sort of animate sausage casing.当大多数人想到“教育”这个词的时候,他们把学生看作是一种活生生的香肠肠衣。