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问题 单项选择题

传输控制（TCP）协议和用户数据报（UDP）协议是互联网传输层的主要协议。下面关于TCP和UDP的说法中，（）是不正确的。

A.TCP是面向连接的协议，UDP协议是无连接的协议

B.TCP能够保证数据包到达目的地不错序，UDP不保证数据包传输的正确顺序

C.TCP协议传输数据包的速度一般比UDP协议传输速度快

D.TCP保证数据包传输的正确性，UDP在传输过程中可能存在丢包现象

答案

参考答案：C

填空题

对于一个化学反应能否自发进行可用ΔH－TΔS判断，若ΔH－TΔS<0，反应能自发进行；若ΔH－TΔS>0，反应不能自发进行。汽车尾气中的主要污染物是一氧化氮以及燃料燃烧不完全所产生的一氧化碳，它们是现代化城市的重要大气污染物。为了减轻大气污染，人们提出用以下反应来治理汽车尾气：2NO(g)＋2CO(g)＝N2(g)＋2CO2(g)，你能否判断这一方案是否可行？理论根据是什么？(已知在298K、101kPa下，该反应的ΔH＝－113.0kJ·mol-1，ΔS＝－145.3J·mol-1·K-1)

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单项选择题

A narrowing of your work interests is implied in almost any transition from a study environment to managerial or professional work. In the humanities and social sciences you will at best reuse only a fraction of the material (1) in three or four years’ study. In most career paths academic knowledge only (2) a background to much more applied decision-making. Even with a " training " form of degree, (3) a few of the procedures or methods (4) in your studies are likely to be continuously relevant in your work. Partly this (5) the greater specialization of most work tasks compared (6) studying. Many graduates are not (7) with the variety involved in (8) from degree study in at least four or five subjects a year to very standardized job (9) . Academic work values (10) inventiveness, originality, and the cultivation of self-realization and self-development. Emphasis is placed (11) generating new ideas and knowledge, assembling (12) information to make a " rational " decision, appreciating basic (13) and theories, and getting involved in fundamental controversies and debates. The humanistic values of higher (14) encourages the feeling of being (15) in a process with a self-developmental rhythm. (16) , even if your employers pursue enlightened personnel development (17) and invest heavily in " human capital " —for example, by rotating graduate trainees to (18) their work experiences—you are still likely to notice and feel (19) about some major restrictions of your (20) and activities compared with a study environment.

9（）

A.peculiarities

B.means

C.satisfactions

D.demands
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