PROBLEMS OF LIVING IN CITIES

Today, over half of the world’s population live in urban areas. Many people are working hard to examine and find solutions for the problem of living in cities in countries all over the world. People are packed into buses and trains like sardines. There are long lines at places like the post officei the grocery store, an the bank. The highways are full of cars and the sidewalks teem with people. Unfortunately, these are true for many major cities. People live in cardboard shacks on the outskirts of the city. They look forward in mountains of garbage. Also, these problems have become more accute as cities have grown larger. In fact, the most important problems are the provision of an adequate water supply, water pollution and air pollution. Although, living in the cities provides a lot of advantages, it may make our lives much more difficult. For example, sometimes it may be required to remain in traffic for hours during the day.

SPACE MACHINES

The satellites are things that go around the sun or a planet at the same speed all the time. The earth is one of the satellites of the sun. The earth’s biggest satellite is the moon. There have been hundreds of man-made satellite since Russia launched the first man-made satellite in 1957.

              There are military, communication, survey, weather, navigation, and laboratory satellites. Military satellites have cameras which can see what is happening in other countries. Communication machines , that is called Comsats, travel through space at the same speed that the earth turns so that they are always over the same place. Comsats carry thousands of messages each minute.

              Map makers are drawing much more accurate charts and maps. They have photos from survey satellites showing exactly where everything is. They can see when a storm is forming, and they can tell how long it will take to strike.

              Laboratory satellites are usually the only ones that have people in them.