A thermos flask consists of two very thin walls of glass with a vacuum between them, which means that the air and everything else has been extracted.

• 热水瓶是由两层很薄的玻璃构成的。在两层玻璃壁之间是一个真空。所谓真空是指在两层玻璃壁之间的空气以及其他一切东西都抽掉了。