人类居住的地球表面越来越不堪重负，人口在几科无节制地增加，而耕地良田却被一幢幢现代化的高楼大厦取而代之，再加上环境污染、空气恶化‘交通拥挤，使得地球表面人类的生存空间变得越来越小。于是乎科学家大声疾呼：人类应寻求与开发新的生存空间。新的生存空间无外乎天上 The surface of the Earth upon which humans live is becoming increasingly overwhelmed. The population has increased uncontrollably in a few sections, and the cultivated fields of arable land have been replaced by a modern high-rise building. Together with environmental pollution and deteriorating air, ’the traffic congestion has caused the human face on the earth’s surface. The living space becomes smaller and smaller. Then the scientists shouted: People should seek and develop new living spaces. The new living space is nothing more than heaven