Read the text below. For questions 16 to 19, choose the best answer (a, b, c or d).
‘Heavier than air flying machines are impossible,’ said the well-known scientist Lord
Kelvin in 1895. Thomas Watson, the chairman of IBM in 1943, was wrong too when he
said that he thought there would be a world market for only five or so computers.
Predictions can, of course, be wrong, and it is very difficult to predict what the world will
be like in 100, 50, or even 20 years from now. But this is something that scientists and
politicians often do. They do so because they invent things and make decisions that shape
the future of the world that we live in.
In the past they didn’t have to think too much about the impact that their decisions had on
the natural world. But that is now changing. An increasing number of people believe that
we should live within the rules set by nature. In other words, they think that in a world of
fixed and limited resources, what is used today will not be there for our children. We
must therefore look at each human activity and try to change it or create alternatives if it
is not sustainable. The rules for this are set by nature, not by man.