The earliest maps were probably drawn in the Middle East. Some of these maps have1and they show us the people at that time thought the earth flat(平的).As time went by, the pictures became more detailed and maps were more2made. Later on, ancient Greeks(希腊人)used their3of math and science to make maps. Greek maps tell us the Greeks knew the world was 4.

    From simple pictures, mapmaking has turned into a science. Maps are made5 surveying(勘测)land. In the1900s, people around the world started to share information to make6maps. With the help of the photographs taken from the sky and space, maps are now more exactly made than ever.7the world is always changing, we will always need new maps.

    There are many types of maps, but almost all use8and pictures to describe what a place is like when the map is made. A map usually tells what the pictures 9. Some maps may show the whole world. A road map will help you know the10from one place to another. Other maps may use pictures to show the temperature and population in different places.

Playing with apps on smart phones is very common among young people. Let's try some special apps and enjoy them.

    When the weather is hot, you go to a lake or an ocean. When you are near a lake or an Ocean, you feel cool. Why? The sun makes the earth hot, but it cannot make the water very hot. Although the air over the earth becomes hot, the air over the water is still cool. The hot air over the earth goes up. Then the cool air over the water moves in and takes the place of the hot air.

    Then you may ask, "Why is the ocean full of salt?" Scientists will say that the salt comes from the rocks. When the rocks get very hot or very cold, they crack (爆裂). Rain falls into the cracks. The rain then carries the salt into the earth and into the rivers. The rivers carry the salt into the ocean. And then you may doubt, "But the ocean does not get more salty every year. Scientists are not sure about the answer to this question.

    We know a lot about our world. But there are still many answers that we do not have, and we are curious about them.

Imagine （想象） walking into a movie theater without being greeted by the smell of popcorn. It's hard to believe, isn't it? For many people, popcorn goes hand in hand with movies. They can't have one without the other. But 1  did this happen?

The 2  between the two is younger than you may think. In the mid-1800s, popcorn was already a popular snack in America. Vendors sold it on the 3  . People, especially kids, loved this street food. In the early 1900s, vendors started to sell popcorn 4  movie theaters.

However, theater owners didn't like popcorn. They believed it would make the experience of watching a movie 5  enjoyable. Eating it would make too much noise during the silent movies.

Later, when movies added sound, the 6  noise problem went away. More and more people went to the movies. Some of them even secretly（秘密地） took popcorn into the theaters. Later, more movie theaters 7  . Some of them agreed people to eat popcorn while they were watching movies.

In the 1930s, the theater owners found that people didn't need to buy popcorn from street vendors. Because popcorn was 8  to make, they could make and sell it themselves. They did that and the smell of popcorn drew more people to their theaters. The 9  made a lot of money, and people enjoyed themselves at the movies.

Today, popcorn is still an important part of the movie-going experience. Roles, a man who once ate three bags of popcorn, said, "People come to theaters sometimes just for the 10 . They don't even care what is playing!"

Oceanic islands, located far out in the ocean, are usually the tops of underwater volcano. These volcanic islands are formed when underwater volcanoes crupt(爆发). 

In August 1883, an ocean ic island called Krakatau in Indonesia was blasted apart by volcanic eruptions. It was one of the most violent cruptions in the world. The effects(影响) of this volcanic eruption was both immediate and long-term

In the "immediate" part, two-thirds of the island disappeared buncâth the sea. Pour huge eruptions created tsunamis (huge waves) that rose 120 feet high. More than 30, 000 people drowned in the tsunamis, which caused floods as far away as San Francisco and the English Channel. Tens of thousands of people on ncarby Indonesian islands were killed by walls of water, hot clouds of volcanic ash, gas, and rock.

In the longer term, climate patterns(气候模式) after Krakatoa's eruption influenced the whole world. The huge amounts of as h and gas entered into the sky and caused clouds to throw back more light than normal, cooling the Eorth. The following year, average(平均的) temperatures dropped by as much as 2. 2 degrees Fahrenheit. A few degrees F dropping n. ay not sound like much, but it is a big deal to plants and animals. 

In general, volcanoes cause lots of changes to the world's geography and climate. Although scientists are becoming better at finding when and where volcanoes will erupt, we must still respect the nature's power. 

A. Hong Kong is called the Shopping Paradise in Asia, People can buy almost everything in Hong Kong such as the latest fashions, all kinds of toys, digital products and so on.

B. When people talk about Chengdu, the first thing that comes to their minds is pandas. Chengdu Giant Panda Breeding Research Base is a must- visit place in Chengdu, especially for those planning to go on a panda tour around Sichuan.

C. Harbin lies in the south of Heilongjiang Province in China. With a 190- day freezing(极冷的) season, Harbin is known as the" City of Ice". If you are a fan of ice sports, you can't miss the place.

D. As one of the oldest cities in China, Xian is world- renowned for the many cultural and historical sites around the city. It's called the" Natural History Museum", which records the great changes of China just like a history book.

E. Because of Guangzhou's special geographical location, people there feel like they are in spring all year round. That's why it is called the" Flower City". Different kinds of flowers are on show at the Spring Festival Flower Fair every year.

F. Shanxi is the province with the largest number of ancient architectural(建筑的) site s in the country. It is known as the" Ancient Chinese Architecture Museum of Art". The most attractive buildings in its capital city Taiyuan are the Jinci Temple and Twin Pagoda Temple.