A、Their average life span was less than 50 years. B、It was very common for them to have 12 children. C、They retired from work mu

W: Hi, Professor Smith. I hear you’ve written a book titled Visions.
M: Yes. It explains how science will revolutionize the 21st century.
W: Could I ask you some questions concerning the book?
M: Sure!
W: Are you optimistic about the future?
M: Generally, yeah! If we go back to the year of 1900, (22) most Americans didn’t live beyond on the age of 50. Since then, we’ve had improvements in health care and technology. There’s no reason why this won’t continue far into the 21st century.
W: Are we ready for the changes that will come?
M: Changes are already happening. The future is here now. We have DNA, micro-chips, the internet. Some people’s reaction is to say we are too old, we don’t understand your technology. (23) My reaction is to say we must educate people to use new technology now.
W: Is world population going to be a big problem?
M: Yes and no. (24) I think that world population will stop increasing as we all get richer. If you are part of the middle class, you don’t want or need twelve children.
W: Will there be a world government?
M: Very probably. We have to manage the world and the resources on the global level because countries alone are too small.
W: Will we have to control over everything?
M: I think we’ll learn to control the weather, volcanoes and earthquakes, illness won’t exist, we’ll grow new livers, kidneys, hearts and lungs like spare parts for a car. People will live to about 230 or about 250. (25) For 2000 years, we have tried to understand our environment. Now we will begin to control it.

Questions;
What does Professor Smith say about most Americans around the year of 1900?
What does Professor Smith advise we do?
When will the world population stop growing according to Professor Smith?
What does Professor Smith think human beings will be able to do?