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The passage tells us that the average length of time an animal species lives

1. 
   cannot be determined until the individual has died
   
2. 
   is more affected by environment than anything else
   
3. 
   always changes when its environment is modified
   
4. 
   can be planned by scientists who study genetics
   
5. 
   depends primarily on its genes, but can be affected by other factors
   

2. 
   Experiments have demonstrated that underfed rats live longer
   

1. 
   but only if they live in very cold places most of the time
   
2. 
   although they also appear to develop emotional problems
   
3. 
   though when their diet is devoid of carbohydrates and vitamins, but not proteins
   
4. 
   and the same appears to hold true for people and other mammals
   
5. 
   though this doesn't necessarily seem to be true for humans
   

3. 
   Geriatric medicine aims to lengthen human life by.
   

1. 
   getting rid of the diseases that shorten it
   
2. 
   creating medicine especially for old people
   
3. 
   encouraging people to live naturally
   
4. 
   restricting the individual's food consumption
   
5. 
   preventing the complications resulting from vitamin deficiency
   

190 THE INTERNET
The Internet originated as a system used for research by the military in the USA. Universities were the next group to connect to the system. The Internet started to develop as a commercial system in the late 1980s, and by the mid-1990s, home users were starting to connect to the Internet in significant numbers. Internet usage is still growing quickly and the number of hours we spend online is rising sharply.
The United States still leads the way in Internet usage, but Europe is catching up. It is difficult to predict anything in such a fast-growing area, but at the end of 1999, it was estimated that between 13 and 14 million people in the UK - about one-fifth of the population - had access to the Internet, while worldwide, at least 100 million people are connected to the system. E-mail is the simplest application of the Internet, but it is also the most popular with both businesses and personal users. E­mail is a straightforward and cost-effective way of communicating using Internet, falling somewhere between the phone and the fax in terms of formality and speed. E-mail is cheap and it only takes a few seconds for a message to reach the Internet. At the moment, the computer is the most common way people connect to the Internet, followed by mobile phones, but in the future, television sets will also have Internet capabilities.

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