题目内容：

Plastic is one of the most important technological discoveries of the 20th century. However, it may soon be replaced. The new development- liquid wood- can replace plastics in all branches of modern-day industries.

Plastic as a material enjoys the biggest demand in the modern world, but it does have a number of drawbacks. First and foremost, plastic isn’t recyclable. Secondly, it contains toxins (毒物) helping develop cancerous diseases. Finally, it’s made of oil and oil reserves aren’t endless.

The liquid wood technology is likely to replace plastic and providing mankind with new materials for many years ahead. Norbert Eisenfreich, a senior researcher at the Faunhofer Institute for Chemical Technology in Germany (ICT), said that arboform, the new material, is made of lignin(木素质）, which can be obtained from soft tissues of wood. Once mixed with several other matenals, it turns into solid and non-toxic alternative for plastics.

ICT team leader Emilia Regina Inone-Kauffmann said the wood-working industry separates wood into three basic components, including lignin. Lignin isn’t used for the production of paper. Specialists of ICT mixed lignin with several natural materials and thus invented the material which could be melted and molded (铸型）.

When solid, arboform looks like plastic and possesses tho qualitie of polished wood. It can be used for the production of any items. Arboform is already used for the production of car parts which require extra strength. In addition, liquid wood can be recycled repeatedly. The material preserved all of its qualities even if it’s reprocessed ten times.

However, the new invention doesn’t enjoy an extensive use due to the high content of sulfur(硫) in it. German researchers are sure to reduce the amount of sulfur by 90% very soon to make arboform usable for home needs.

71. According to the passage, plastic        .

A. helps us to reduce the use of petrol

B. helps to protect our environment in some way

C. does harm to our society in some way

D. has been replaced by the newly discovered material

72. What’s the advantage of arboform over plastic?

A. It is easier made from natural oil.

B. It is more widely used in household

C. It is recyclable and friendly to environment.

D. It contains no poisonous materials.

73. The underlined word “altemative” in Paragraph 3 means        .

A. lignin or arboform                                B.soft tissues of wood

C. plastics or wood                                    D. mixture of several materials

74. It can be concluded that German researchers will focus their future work firstly on     .

A. the material’s extensive use                    B. the content of sulfur in arboform

C. the production cost of arboform                     D. the qualities of liquid wood

75. The main purpose of the text is to     .

A.introduce liquid wood which will replace plastic

B.show readers how to produce arboform

C.advertise the new material-arboform

D.advertise new products made of arboform