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8. travelling
it is exciting to visit different places. as you travel, you will see beautiful sceneries typical of the region. besides, you can meet and make friends with people of different colors and races. finally, you can get to know the customs and living habits of the local people. today people are so fond of travelling that tourism has become one of the faster growing industries in most countries.
the main reason why people travel is, perhaps, for pleasure. for example, having worked hard throughout the weekdays, people will find a widened trip to the nearby mountains or beaches a real relaxation. for another example, spending an annual holiday travelling abroad is an especially satisfying experience for those who do not have much of an opportunity to be away from their homelands. when people return from their travel, they will generally feel fresh and energetic, ready to work harder.
travelling is also one of the best means for learning. you may have read or heard about something but you can never get an accurate picture of it until you see it for yourself. seeing is believing. furthermore, if you area careful observer, you can learn much during your travel about the geography, biology, and history of the places you visit. no matter how well educated you are, there is always a lot for you to learn through travelling. the knowledge acquired from travel, as you will have found in your life, is no less valuable than that from any influential reference book.
9. the world population explosion
the human race has experienced a consistent increase in population since the beginning of its history. famine and disease have done little to offset(抵消)this steady increase. too many people are added annually to the population of the world. so both the causes of population increase and the results of having more people are worth careful study.
culture evolution is the major factor responsible for population increase. early in human development, people invented tools to hunt animals. later they built shelters to protect themselves. step by step, they made life easier. as a result, fewer died from natural forces, such as harsh climate and disease.
in the past, when population grew, there was unexplored territory to inhabit. but now, almost all the habitable land has been explored.
the world’s population may reach 8.7 billion in 2033. it is clear that world population is a serious issue that needs careful attention. human beings are unique to solve problems through cultural evolution.(發(fā)展) facing the world population explosion in the near future. we must carry out the birth control program in order to save the mankind and save the world.
