TuYI2.2 - Lesson F (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!