Question

GIRLS...❤ [ydbkecvzjv]​

Answer 1

Because a thermos flask works by restricting the transfer of heat (energy) to and away from the contents. The inner tube is isolated from the external case by a vacuum. This prevents the transfer of energy, say heat, into the inner chamber where there is a cold beverage.

Simple and effective solution to a global need; keeping tea hot and gin and tonics cold.