📝 Module 7 Section 2 - Exercise 10

These days the onset of decay in plastics can be put back significantly by adding anti-aging compounds that block the initial harmful effects of air and sunlight by acting like a sunscreen. Unfortunately, these additives are so costly that manufacturers do not use them unless absolutely necessary. Eventually, these additives also lose their effectiveness. Developing conservation strategies is made more challenging due to the variety of ways in which different plastics degrade. What works to preserve one material can catastrophically shorten the lifetime of another. Most modern plastics decay primarily through reactions with oxygen and are best preserved by sealing them in an oxygen-free atmosphere. Yet cellulose acetate needs exactly the opposite treatment; without a good supply of fresh air, the decay is accelerated.
1. The list below gives some of the reasons why the conservation of plastics is a difficult task. Which **TWO** of these reasons are mentioned by the writer of the text? 请选择 2 个答案
A. There are not enough trained conservationists.
B. Preservatives have only a temporary effect.
C. New plastics are less stable than older ones.
D. Different plastics react differently to conservation techniques.
E. Museums are reluctant to spend on conserving plastics.
2. The article discusses an infrared gun which is used in plastics conservation. Which **TWO** of the following statements are made about the infrared gun? 请选择 2 个答案
A. It can damage plastics if it is used repeatedly.
B. It can be used on other materials.
C. It can only be operated in a darkened room.
D. It took a long time to design.
E. It will soon have an additional application.