Plastics are materials which are softened by heat and set into lasting from when shaped in a mold. Some are natural; some are semisynthetic, the result of chemical action on a natural substance; some are synthetic, built up from the constituents of oil or coal. All are based on the chemistry of carbon, with its capacity for forming chains. The molecules that compose them (monomers) link together in the setting or curing(固化) process to form chains (polymers), which give plastics their flexible strength. Some plastics retain their ability to be softened and reshaped; like wax, they are thermoplastic. Others set permanently in the shapes they are given by heat and pressure; like eggs, they are thermosetting.

From industrial beginnings in the nineteenth century, plastics have struggled through a hundred and twenty years of glory, failure, disrepute(壞名聲) and suspicion on the slow road to public acceptance. Now, at last, one can positively say that plastics are appreciated and enjoyed for what they are; that they make modern life richer, more comfortable and convenient and also more funny. Plastics are warm materials, sympathetic to the human touch, and their transformation into things that come into contact with human beings is entirely appropriate.

The fact that there plastic antiques comes as a shock to most people. How can a material that seems so essential in the twentieth century, and one that is so much associated with cheap disposable products, have a histroy at all? It is a young technology, and a great part of the fun of collecting plastics is that beautiful pieces of historical interest can still found very cheaply.

16. Which of the following is the best title for the passage?

(A) The Importance of Plastics in the Nineteenth Century

(B) Why people Are Suspicious of Plastics

(C) The development of Plastics as a Modern Material

(D) How Plastics Are Material

17. Which of the following is necessary to create any type of plastics?

(A) Carbon.

(B) Oil.

(C) Eggs.

(D) Coal.

18. According to the author, for approximately how many years have plastics existed?

(A) 100.

(B) 120.

(C) 140.

(D) 160.

19. What historical information does the second paragraph give about plastics?

(A) They originated primarily as road-surfacing materials.

(B) They have come into general use very gradually.

(C) Their popularity was at its height at the time of the Industrial Revolution.

(D) The earliest types were soft and did not last very long.

20. Why does the author mention antiques in the third paragraph?

(A) Some plastic objects are now considered antiques.

(B) Plastics replicas(復(fù)制品) of valuable antiques are relatively common.

(C) Young collector prefer real antiques to plastic objects.

(D) Dealers use inexpensive plastic parts to repair valuable antiques

答案：C A B B A