How long can human beings live? Most scientists who study old age think that the human body is ___1___ to live no longer than 120 years. However, 110 years is probably the longest that anyone could hope to live —— if he or she is ___2___ healthy and lucky. Some scientists even say we can live as long as 130 years! Yet, our cells simply cannot continue to reproduce ___3___. They wear out, and as a result, we get old and ___4___ die.
Even though we can’t live forever, we are living a ___5___ life than ever before. In 1900, the average American life span (寿命) was only 47 years, but today it is 75 years!
When does old age begin then? Sixty-five may be out-of-date as the ___6___ line between middle age and old age. After all, many older people don’t begin to experience physical and mental ___7___ until after age 75.
People are living longer because more people ___8___ childhood. Before modern medicine changed the laws of nature, many children died of common childhood ___9___. Now that the chances of dying ___10___ are much lower, the chances of living long are much higher due to better diets and health care.
On the whole, our population is getting older. The ___11___ in our population will have lasting effects on our social development and our way of life. Some people fear such changes will be for the worse, while some see ___12___, not disaster, many men and women in their “golden years” are healthy, still active, and young in ___13___ if not in age.
As the society grows old, we need the ___14___ of our older citizens. With long lives ahead of them, they need to ___15___ active and devoted.
1. A. designed B. selected C. improved D. discovered
2.A. completely B. generally C. apparently D. extremely
3. A. rapidly B. harmlessly C. endlessly D. separately
4.A. eventually B. hopelessly C. automatically D. desperately
5.A. busier B. longer C. richer D. happier
6. A. finishing B. guiding C. waiting D. dividing
7. A. stress B. damage C. decline D. failure
8.A. survive B. enjoy C. remember D. value
9. A. problems B. fears C. worries D. diseases
10.A. poor B. young C. sick D. quiet
11.A. changes B. recovery C. safety D. increases
12.A. dreams B. chances C. strengths D. choices
13.A. mind B. appearance C. voice D. movement
14.A. protection B. suggestions C. contributions D. permission
15.A. sound B. appear C. turn D. stay