Choose the best answer to complete the passage 

Paper was __________ (25) by the Chinese in the first century A.D. The art of papermaking took 700 years to reach the Muslim world and another 700 years to get to Britain.

Most paper __________ (26) made from wood. When the trees are cut down, they are carried by land or water to paper mills. Here they are cut up and the wood is __________ (27) up into fibers, mixed with water and chemicals. This wood pulp is then dried up on a machine and made into paper.

Papermaking is an important British industry, and paper from Britain is __________ (28) to South Africa, Australia and many other countries. Some of the wood used in British __________ (29) industry comes from trees grown in Britain, but wood is also imported from other countries such as Norway. One tree is needed for every 400 copies of a forty-page newspaper. If half the adults in Britain each day buy one daily paper, this uses up over 40,000 trees a day. Trees are cut down faster than they can be replaced, so there may be a paper __________ (30) before the year 2020.

(25).......................

• A. 
  invented
• B. 
  invent
• C. 
  be invented
• D. 
  invents