[单项选择]It was probably around 3,000 years ago that people first began making things to help them measure the passage of time. Having noticed that shadows move around trees as the sun moves across the sky, someone drew a circle and put a stick in the center. As the sun passed overhead, people could tell which part of the day it was by noticing which mark on the circle the shadow fell across. These circles were called "sundials". Later, they were made of stone and metal to last longer.
Of course, a sundial did not work at night or on cloudy days, so men kept inventing (发明) other ways to keep track of time. After glass blowing was invented, the hourglass came into use. An hourglass is a glass container for measuring time in which sand moves slowly from the top half to the bottom in exactly one hour. The hourglass is turned over every hour so the sand could flow again.
One of the first clocks with a face and an hour hand was built for a king of France and placed in the tower of his pala
A. Clocks of Our Lives
B. What Can a Clock Tell Us
C. Clock through Time
D. Clocks Change People’s Lives

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