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Risa in Roma, Italy is chatting online with his friend Xiaoming, who has just moved to Beijing, China with his family. After a little while, Xiaoming tells Risa that it’s time for him to go to bed. Risa looks outside to see the sun shining and is confused why Xiaoming would go to bed when it’s so early! “What time is it?” Risa asks. “It’s 9:00 pm!” Xiaoming replies. What’s going on here? Is it some kind of time travel?

In fact, it is NOT. This is actually just something that happens every day to our planet. Risa and Xiaoming are having different times because Xiaoming is now in a different time zone.

A time zone is an area on Earth that has a specific time that all the people in that area can set their clocks to. You’ll pass through different time zones if you travel from east to west (or west to east) on the surface of Earth. Humans came up with the idea of time zones and decided which parts of Earth are in which time zones in the 1880s. The world now has 24 time zones and each time zone is one hour ahead (领先) or behind its neighboring ones. You can see part of these time zones on the map below. The numbers on the map show how many hours you must add to or subtract from the Greenwich Mean Time (格林威治时间) to get the local time.

Most countries, such as Ireland and Japan fall in one zone. Some large countries such as the U.S., Canada and Russia may be divided into three or more time zones. But China is the only large country besides India that only uses one time zone.

We need time zones because Earth is like a ball. Each day, Earth completes one full turn. As it turns, sun shines on only one part of it at a time. While the sun shines where you live, you are having the daytime, but it’s nighttime somewhere else. It would be silly if people all over the world used the same time.

1．Why does the writer mention the story of Risa and Xiaoming?

A．To share this interesting story.

B．To introduce the topic of time zones.

C．To give an example of time travel.

D．To explain how Earth completes a full turn.

2．In Risa and Xiaoming’s story, when it’s 9:00 pm in Xiaoming’s city, what time is it in Risa’s city?

A．2:00 pm

B．4:00 am

C．1:00 pm

D．5:00 am

3．Why do we need the world time zones?

A．Because the world time zones can make time longer.

B．Because it is boring to have just one time zone.

C．Because not all the places can be in the daytime at the same time.

D．Because there are too many countries in the world.

4．Which of the following is TRUE?

A．If you travel from north to south on the surface of Earth, you will certainly pass through different time zones.

B．Time zones are something that naturally happens.

C．China is the only large country in the world that only uses one time zone.

D．Different cities in America may be using different time zones.

5．According to the passage as well as the time zone map, if you know the Greenwich Mean Time, how can you work out New York’s time?

A．By adding 5 hours to the Greenwich Mean Time.

B．By multiplying the Greenwich Mean Time by 5.

C．By subtracting 5 hours from the Greenwich Mean Time.

D．By dividing the Greenwich Mean Time by 5.