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问题 单项选择题

It will be emphasized that commercial space operations are inherently complex, longterm, capital-hungry, and set by a variety of risks.

A. beset by
B. inset by
C. preset by
D. reset by

答案

参考答案：A

解析： beset(后面常与by连用)困扰；inset插页，插入，嵌入(一般不与by连用)；preset预先安置，预先调试，事先调整；reset重新安排。后面三个词大多作及物动词，而本句意为：需要强调的是民用太空计划复杂，耗时长，资金缺且风险重重。因此A为答案。

单项选择题

About fifty years ago, plant physiologists set out to grow roots by themselves in solutions in laboratory flasks. The scientists found that the nutrition of isolated roots was quite simple. They required sugar and the usual minerals and vitamins. However, they did not require organic nitrogen compounds. These roots got along free on mineral inorganic nitrogen. Roots are capable of making their own proteins and other organic compounds. These activities by roots require energy, of course. The process of respiration uses sugar to make the high energy compound ATP, which drives the biochemical reactions. Respiration also requires oxygen. Highly active roots require a good deal of oxygen.
The study of isolated roots has provided an understanding of the relationship between shoots and roots in intact plants. The leaves of the shoots provide the roots with sugar and vitamins, and the roots provide the shoots with water and minerals. In addition, roots can provide the shoots withorganic nitrogen compounds. This comes in handy for the growth of buds in the early spring when leaves are not yet functioning. Once leaves begin photosynthesizing, they produce protein, but only mature leaves can "export" protein to the rest of the plant in the form of amino acids.

Which of the following best describes the organization of the passage

A．The results of two experiments are compared.

B．A generalization is made, and several examples of it are given.

C．The findings of an experiment are explained.

D．A hypothesis is presented, and several means of proving it are suggeste
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多项选择题

在金信工程中，数据质量问题是指数据库中的信息与企业的现状之间存在差异，它的形成原因是（）

A、市场主体的客观情况与工商行政管理档案之间的误差

B、录入过程或数据转换过程中出错，人为录入总会有差错的

C、机器本身的错误

D、数据库设计的原因
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