We are all busy talking about and using the Internet ,but how many of us know about the history of the Internet?

      Many people are surprised when they find that the Internet was set up in the 1960s.At that time, computers were large and expensive. Computer networks(网络)didn' t work well .If one computer in the network broke down, then the whole network stopped. So a new network system(系统) had to be set up. It should be good enough to be used by many different computers. If part of the network was not working, information could be sent through another part. In this way the computer network system would keep on working all the time. At first, the Internet was only used by the government, but, in the early 1970s, universities, hospitals and banks were allowed to use it too.

    However, computers were still expensive and the Internet was difficult to use. By the start of the 1990s, computers become cheaper and easier to use. Scientists had also developed software(软件) that made “surfing(浏览)” the Internet more convenient (方便).

    Today it is easy to get on-line and it is said that millions of people use the Internet every day. Sending e-mail is more and more popular among students.

   The Internet has now become one of the most important parts of people's life.

    The word 'day' has two meanings. When we talk about the number of days in a year. We are using 'day' to mean 24 hours. But when we talk about day and night. We are using 'day' to mean the time between sunrise and sunset. Since the earth looks like a ball. The sun can shine on only half of it at a time. Always one half of the earth is having day and the other half night. A place. is moved from day into night and from night into day over and over by the spinning(旋转)of the earth. At the equator(赤道)day and night are sometimes the same length, they are each twelve hours long. The sun rises at 6 o'clock in the morning and sets at 6 o'clock in the evening. For six months the North Pole is tilted(倾斜)toward the Sun. In those months the Northern Hemisphere(半球)gets more hours of sunlight than the Southern Hemisphere. Days are longer than nights. South of the equator nights are longer than days. For the other six months the North Pole is tilted away from the SUN. Then the Southern Hemisphere gets more sunlight. Days are longer than nights. North of the equator nights ate longer than days. Winter is the season of long nights. Summer is the season of long days.

Many drivers are not very clear about the roads in strange places. Especially, the navigation(导航) just tells the exit number, which makes it easy for drivers to get on the wrong road. However, now you don't have to worry about these complicated(复杂的) roads anymore. Lane(车道)level navigation based on the Beidou satellite system(北斗卫星系统) will be popular in China very soon.

The socalled lanelevel navigation uses highlycorrect technology to show us the real road situation. Compared with past navigation, it can provide exact road guidance in some complicated parts to help drivers choose the best way.

In January 2023, an online map officially introduced an enhanced version(加强版) of lane­level navigation, which helped make good use of the Beidou satellite system more deeply. It greatly improved the speed of receiving information and giving answers and the accuracy of accuracy lanelevel positioning.

In the new version of the online map, lanelevel navigation can be used on all kinds of roads. The new version has a different advantage from the old one: it can guide us clearly where to go in complicated crossings.

In big cities, for drivers who come to these cities for the first time, overhead bridges make it easy to make driving mistakes in strange places. So how does lane­level navigation solve the problem? After careful study, planning and organization, lanelevel navigation uses the Beidou satellite system to improve the positioning accuracy and guide drivers.

For the driverless industry, this map is a good piece of technology, which makes it safer and more widely used.

It's reported that 800 million people around the world have experienced back pain. And many of them find that their pain keeps coming back. ____ But scientists believe that doing one simple thing could help: walking. 

Scientists invited 700 people to take part in a study. Most were women and all of them had recently experienced back pain. The people were put into two groups. One group took part in a walking program and had six meetings with a doctor. People in this group were asked to walk half an hour five days a week, while those in the other group didn't do anything. The scientists followed up the two groups for three years. 

The scientists' findings are surprising. People in the walking group had an average (平均) of  208 days before their back pain recurred, while those in the other group felt the pain again after an average of 112 days. What's more, people in the walking group also made far fewer visits to the doctor. 

Why is walking helpful to lower back pain? Scientists are not yet certain of the reasons. But they think it's probably because walking can get the muscles (肌肉) stronger and improve sleep. As for how to walk, they suggest walking on a flat (平整的) surface. People also should listen to their bodies, as walking too far or for too long could make the pain worse. 

David is a1 boy and he is crazy about space. He always wonders how space stations work. For him, a space camp is2 than any other camp in the world. 

·At the ageof seven, David had3 first astronaut training experience. He and his parents were invited to a Family Space Camp. They had a taste of what it was likc to travel4 space. Everything was magical. 5 excited David was!

David has beento many space camps over the last eight years. Last month, he went to6 new space camp. It had a lot of fun training programs, 7 he enjoyed all of them. There he was often asked8 he liked space camps so much. "I feel like a real astronout in the space camp, and I don't even need9 tne earth, "he said. 

These experiences have influenced his life. Now David10 space science. He has made up his mind to be a space engineer in the future.