How could we tell time if there were no watches or clocks anywhere in the world?
The sun was probably the world’s first “clock”, except in the far north, where the Eskimos(爱斯基摩人) live. There it’s dark most of the winter, and light most of the summer. But in most of the world, people have used the sun for a clock. Even today if you don’t have a clock that shows time, you still know that when the sun shines, it’s day; and when it’s dark, it’s night. The sun can not only tell you whether it’s day or night but also it’s morning, noon, or afternoon. When the sun is almost directly overhead, it’s noon.
People who live near the sea can tell time from the tides. In the daytime, for about six hours, the water rises higher and higher on the beach. And then it goes down and down for another six hours. The same thing happens again at night. There are two high tides and two low tides every 24 hours.
Seamen on a ship learn how to tell time by looking at the moon and the stars .The whole sky is their clock.
In some places in the world the wind comes up at about the same time every day or changes direction or stops blowing. In these places, the wind can be the clock.
A sand clock is an even better clock. If you had fine dry sand in a glass shaped like the one in the picture above, you would have what is called an hourglass. The sand in the hourglass goes from the top part to the bottom part in exactly one hour. When the hourglass it turned over, the sand will take another hour to go back again.
The Eskimos in the far north can’t use the sun for a clock because ______.

A．they know very little about the sun

B．the sun there never goes down in winter.

C．it’s too cold for them to go out to watch the sun

D．there are long dark winters and long light summers in the far north

The underlined word “tides” in paragraph 3 means ___________.

A．ocean current

B．storm

C．a regular rise and fall of the sea

D．wave

In which part of the newspaper can you probably read this passage?

A．News	B．Science
C．Business	D．Advertisement

What’s the best title for the passage?

A．Different Ways to Tell Time

B．Useful Machine to Tell Time

C．The History of the Clock

D．The Development of the Clock

How many ways are mentioned in the passage to tell time?

A．Five

B．Four

C．Six

D．Three