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问题 选择题

利用原料气在合成塔中合成NH3，为加快正反应速率，且提高N2的转化率所采取的措施是 （   ）。

A．加压

B．移走氨气

C．使用催化剂

D．充入N2

答案

答案：A

题目分析：氨气的生成是体积减小的可逆反应，所以为加快正反应速率，且提高N2的转化率，可以通过加压的方法实现，A正确。B中反应速率降低，C中转化率不变，D中氮气的转化率降低，答案选A。

点评：该题的关键是在明确可逆反应特点的基础上，灵活运用外界条件对反应速率和平衡状态的影响，有助于培养学生的逻辑推理能力和灵活应变能力。

单项选择题

For many people today, reading is no longer relaxation. To keep up their work they must read letters, reports, trade publications, interoffice communications, not to mention newspapers and magazines: a never-ending flood of words.
In (36) a job or advancing in one, the ability to read and comprehend (37) can mean the difference between success and failure. Yet the unfortunate fact is that most of us are (38) readers.
Most of us develop poor reading (39) at an early age, and never get over them. The main deficiency (40) in the actual stuff of language itself—words. Taken individually, words have (41) meaning until they are strung together into phrases, sentences and para-graphs. (42) , however, the untrained reader does not read groups of words. He laboriously reads one word at a time, often regressing to (43) words or passages.
Regression, the tendency to look back over (44) you have just read, is a common bad habit in reading. Another habit which (45) down the speed of reading is vocalization—sounding each word either orally or mentally as (46) reads. To overcome these bad habits, some reading clinics use a device called an (47) , which moves a bar (or curtain) down the page at a predetermined speed. The bar is set at a slightly faster rate (48) the reader finds comfortable, in order to "stretch" him.
The accelerator forces the reader to read fast, (49) word-by-word reading, regression and sub vocalization, practically impossible. At first (50) is sacrificed for speed. But when you learn to read ideas and concepts, you will not only read faster, (51) your comprehension will improve.
Many people have found (52) reading skill drastically improved after some training. (53) Charlce Au, a business manager, for instance, his reading rate was a reasonably good 172 words a minute (54) the training, now it is an excellent 1,378 words a minute. He is delighted that how he can (55) a lot more reading material in a short period of time.

[A] for[B] in[C] after [D] before
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