A. running B. that C. solution D. received E. result F. surface G. launched H. set I. which J. reached K. land L. changing M. soil N. jumping O. became P. area Q. stand R. high Earth is a lovely blue and green planet. It has air and water. It has land for growing crops and grazing animals. Why would anyone want to leave our planet and live in a space colony? One reason is that Earth is getting overcrowded. In 1950, Earth’s population was 2.5 billion. In 1980, it …( 1 ) ... 4.4 billion. By the year 2050 it may be more than 9 billion. Such a large population will mean less food and less room for each person. One …( 2 )… would be for some of the people to live in space colonies. Another reason is that Earth has only so much oil and natural gas. We are already …( 3 )… low on these fuels. One day we may run out of them altogether. In space, on the other hand, there are almost endless sources of energy. After years of preparation and testing, in the summer of 1969 America was finally ready to … ( 4 ) … a man on the moon. The three astronauts, Neil Armstrong, Edwin “Buzz” Aldrin and Michael Collins, were…. ( 5 ) … aboard the Saturn V rocket on July 16th, 1969. After a four-day trip to reach the moon, Neil Armstrong and Buzz Aldrin used the lunar module to descend to the moon’s … ( 6 )…. while Michael Collins remained in orbit around the moon in the Command module. After landing on the Moon, Armstrong climbed down the ladder and became the first human being to …( 7 )… foot on the Moon. He was soon joined by Aldrin, and the two men spent more than two hours walking on the lunar surface. They gathered 21 kg of soil samples, took photographs and set up some scientific experiments. When the time came to leave, the astronauts took off from the Moon in the top part of the lunar module and rejoined Michael Collins in the command module, …( 8 )… had been circling above. Then they fired the spacecraft’s main engine and headed back to Earth.