Passive Voice

In 1900 there were 1.6 billion people in the world, but today that number is over 6 billion. In the last century, a lot of the world’s forests 1_______ (destroy) to provide wood for making furniture and paper.

In addition, many of the world’s seas and rivers 2______ (pollute).

Another problem today is how to provide food for the growing number of people in the world. New ways of growing food 3______ (need) very soon.

Some new foods 4______ (discover) by scientists in the last few years, and in the future we will eat more of these.

Living space will be another big problem in the future. Perhaps one day new cities 5______ (not build) on land any more − we will build them on or under the sea!

Since computers were invented, they 6______ (use) by people in many different ways.

For example, computer-controlled robots 7______ (give) jobs in factories because they can do some things much faster and better than people.

But some people are worried about this. They think that our world 8______ (control) by computers and robots one day.

Some robots can learn from their mistakes, and one day they may become intelligent. In the future perhaps all the important decisions 9______ (make) by robots.

And when that happens, people 10______ (not need) any more!