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问题 单项选择题

以下（）因素有可能使设备中原来存在的，制造规范允许的小缺陷扩展开裂，或使设备中原来没有缺陷的地方产生这样或那样的新生缺陷，最终导致设备失效。

A.高温和应力作用导致材料蠕变

B.由于温度、压力的波动产生交变应力，使设备的应力集中部位产生疲劳

C.由于腐蚀作用使壁厚减薄或材质劣化

D.以上都对

答案

参考答案：D

选择题

磁带录放机可高速播放正常录制的声音，在高速播放时最有可能听不到的声音是正常录音时( )

A．音调较低的声音

B．音调较高的声音

C．响度较小的声音

D．响度较大的声音
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问答题

Passage 2 Ladies and Gentlemen, Ten years ago, food safety was not on many people’s mind in Europe. We all expected our food to be safe, not only because it generally was safe, but also because incidences of chemical or microbiological contamination were local in nature. So was the reporting about them. A conference like this one would not generate much interest beyond the people present. // What a contrast with the present. Today, food safety is one of the highest priority issues for consumers, producers and governments alike, all over Europe. // What has caused this change The occurrence of BSE, of course, which brought with it the link to the terrible and fatal Variant Creutzfeldt-Jakob disease, created a widespread and deep-set unease about meat products. Yet, for a long time, continental Europeans left the worrying to the unfortunate British, safe in their conviction that the danger was contained by the Channel. // No longer. The consequences of BSE are felt across Europe and beyond. And the recent occurrence of foot-and-mouth disease spread alarm across Europe in a matter of days. even though it has no direct relation to human health. Through such and other incidents, European consumers have woken up to the reality that the trade in food and farm products is truly international—not least because countries of origin are clearly marked on supermarket produce. They are starting to discover the intricate network of international trade that underlies the food industry and brings products to supermarket shelves. // Still, based on evidence, it is clear that the main food safety problems are not the spectacular outbreaks which make their way into the media. In fact, the problem is a vast number of sporadic cases, many of which not only fail to reach the headlines; they don’t even make it into our reporting system. // As I look at the vast area of food safety from the point of the World Health Organization, I see three major challenges to protect the health of the consumer: 1) We need to accept that the systems we use in Europe to ensure food safety are not as good as we have come to believe. To improve these systems and re-establish consumer confidence, we must reassess them all the way from the farm to the table; // 2) We need to ensure reasonable food safety standards that apply throughout the world and assist all countries to reach these standards. In the long run, it is in our own self interest to do so. Secondly, unless we do so, developing countries cannot participate in global trading systems: // 3) We must develop global standards for pre-market approval systems of genetically modified food to ensure that these new products not only are safe, but also beneficial for consumers and more efficient than existing products. // (Excerpts from the speech "Food Safety—a World-wide Challenge" by Dr. Gro Harlem Brundtland, former Director-general of World Health Organization, Uppsala, Sweden)
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