计时器
One day he asks you to prepare breakfast for him, and the only timepieces in the house are two hourglasses. 一天，他让你为他准备早饭，而家里能找到的计时器只有两个沙漏。
The development of mechanical timepieces witnessed the search for more accurate sundials with which the timepieces could be regulated. 由于机械计时器的发展，人们开始寻求更精确的日晷，以便校准机械计时器。
