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问题 问答题

简述引起食品腐败变质的原因。

答案

参考答案：[答案] (1)食品本身的组成和性质。动植物食品本身含有各种酶类。在适宜温度下酶类活动增强，使食品发生各种改变，如新鲜的肉和鱼的后熟，粮食、蔬菜、水果的呼吸作用。这些作用可引起食品组成成分分解，加速食品的腐败变质。
(2)环境因素。主要有温度、湿度、紫外线和氧等。合适的环境温度可加速食品内的化学反应过程，且有利于微生物的生长繁殖。水分含量高的食品易于腐败变质。紫外线和空气中的氧均有加速食品组成成分氧化分解作用，特别是对油脂作用尤为显著。
(3)微生物的作用。在食品腐败变质中起主要作用的是微生物。除一般食品细菌外尚包括酵母与真菌，但在一般情况下细菌常比酵母占优势。微生物本身具有能分解食品中特定成分的酶的能力，一种是细胞外酶，可将食物中的多糖、蛋白质水解为简单的物质；另一种是细胞内酶，能分解细胞内的简单物质，其产物能使食品具有不良的气味和味道。

单项选择题

诊断肺脓肿最主要的依据是（）

A.右肺门上方见团块状密影，边缘分叶状，其内可见偏心空洞

B.右上肺可见片状阴影，其内可见透光区

C.右下肺野类圆形阴影，边缘光滑，其内见液气平面

D.右下肺可见大片状实变阴影，边缘模糊，其内可见空洞及液气平面

E.两肺可见部位不定之薄壁透光区，其内见液气平面
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单项选择题

Questions 26～30


Extract 1


Simply put, a newspaper editorial is an article that expresses an opinion. While this single sentence may not seem to do justice to defining what an editorial is, think about this brief definition. What other types of article express this defining characteristic What other articles actively promote the expression of an opinion Reviewers may include factual information, so their personal opinions do not totally dominate a review, and news reporters attempt to give "just the facts" about a situation. Editorials are one of the few types of articles that celebrate the expression of opinion; they are wholly centred on the opinion being presented by the writer and the debate and discussion that the opinion incites.
That said, an editorial writer often attempts to the best of his or her own ability to defend the opinion that is being presented against potential counterarguments—a good editorial does not appear in a vacuum; this defence employs argument, logic, and other appeals to readers in an attempt to achieve a desired effect. The purpose of any given editorial is entirely directed by its writer. Most often, however, editorial writers seek to prove the validity of an opinion through argument, point out something that has been ignored, or simply create discussion about a topic. In sum, most editorials will inevitably involve the defence of an opinion in the hopes of advancing some goal that the writer has in mind.

Extract 2


If you want to become a music journalist, there are several starting points. One is to have a good knowledge of the greats, because when you write you have to put today’s music into context. It isn’t enough simply to be familiar with the music of the last five years. Another way is to specialize in a particular type of music, such as folk, country or techno. And the third starting point is to be a musician. This opens doors to the magazines targeted specifically at musicians rather than a more general readership. There may be opportunities if you don’t fit any of those three categories, but it’s a competitive marketplace so it’s important that in some way you meet the sometimes quite specific needs of the music magazines.
Staff jobs do get advertised from time to time, but your best approach might be to work freelance. This way you can do non-music writing as well, if necessary, to add to your income, and equally importantly, you’ll have greater creative freedom by writing for different music magazines. In general they make sure they meet their readers’ very specific expectations, and so you may find writing just for one is limiting.

Extract 3


This book was published before under a different title and the material has been reissued in the A Very Short Introduction... series of titles which aim to give readers a brief, colourful insight into a subject and ignite a passion for further learning and discovery. The series is an alternative to the Introducing... series of yesteryear, which briefly introduced readers to people, topics and ideas. Journalism: A Very Short Introduction suffers where the Introducing... titles excelled. Humour was used by the Introducing... series to great effect to draw the reader in and make the subject covered that much more interesting. So much rests on how a subject is taught, and being likened to a textbook, which is a real risk in the present case, would be the kiss of death for a title such as this.

According to the second paragraph of Extract 1, editorial writers are likely to ______.

A. explain the circumstances in which they could change their opinion
B. claim to have opinions that they do not really hold
C. take other people’s opinions into account
D. summarize other writers’ opinions on the same topic
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