填空题

People have dreamed of traveling in space for thousands of years. But it was not until 1957 that it became a (36) On October 4,1957 Russia (37) the first man-made satellite into space, It was called Sputnik I. On April 12,1961 the Russian (38) Yuri Gagarin became the first man to orbit the Earth. The first spacewoman in the world was Valentina Tereshkova. She made 48 (39) in 1963 in her Vostok 6. On July 20,1969 the American (40) Neil Armstrong became the first man to set foot on the Moon. In 1986 the Russian space station Mir was launched. Scientists are already at work on the (41) Space Station, a "city of space". It will be the size of a football field and will (42) over 200 tons. A team of 10 --15 spacemen will (43) be able to live and work at the International Space Station in 2005. The next step will be the first moon base. 20 or 30 scientists will live inside a dome with an artificial atmosphere. (44) It also means that they will be able to grow food. (45) Scientists say that the planet once had water on its surface. If that water is now frozen underground, humans will be able to use it someday. By the end of the 21st century, scientists hope, (46)