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问题 计算题

如图所示，同学们用水桶提水，给刚刚栽上的树苗浇水。已知桶的质量是1kg，容积都是15L （ρ水=1.0×l03 kg/m3、g取10N/kg）。则：

（1）桶装满水后，总重为多少牛？

（2）小红用150N的力能否提起一桶水？

答案

解：

（1）装满水后，桶中水的质量m水=ρ水V水=1.0×103kg/m3×15×10-3m3 =15kg，桶中水重G水＝m水g=15kg×l0N/kg=150N，桶重G桶=m桶g= 1kg×10N/kg=l0N，桶中装满水后总重G总=G水+G桶=150N+10N =160N；

（2）因为150N<160N，所以小红无法提起一满桶水。

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 (1) a job or advancing in one, the ability to read and comprehend (2) can mean the difference between success and failure. Yet the unfortunate fact is that most of us are (3) readers. Most of us develop poor reading (4) at an early age, and never get over them. The main deficiency (5) in the actual stuff of language itself—words. Taken individually, words have (6) meaning until they are strung together into phrases, sentences and paragraphs. (7) , however, the untrained reader does not read groups of words. He laboriously reads one word at a time, often regressing to (8) words or passages. Regression, the tendency to look back over (9) you have just read, is a common bad habit in reading. Another habit which (10) down the speed of reading is vocalization—sounding each word either orally or mentally as (11) reads.
To overcome these bad habits, some reading clinics use a device called an (12) , which moves a bar(or curtain) down the page at a predetermined speed. The bar is set at a slightly faster rate (13) the reader finds comfortable, in order to "stretch" him. The accelerator forces the reader to read fast, (14) word by word reading, regression and subvocalization practically impossible. At first (15) is sacrificed for speed. But when you learn to read ideas and concepts, you will not only read faster, (16) your comprehension will improve. Many people have found (17) reading skill drastically improved after some training. (18) Charlie Au, a business manager, for instance. His reading rate was a reasonably good 172words a minute (19) the training; now it is an excellent 1,378 words a minute. He is delighted that how he can (20) a lot more reading material in a short period of time.

A．master
B．go over
C．present
D．get through
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单项选择题

An analyst gathered the following information about a company:
Net profit margin 5.0%
Total asset turnover 2.0
Total assets/equity 2.5
Beta for the company's stock 1.5
Expected rate of return on the market index 10.0%
Risk-free rate of return 5.0%
The analyst expects the information above to accurately reflect the future. If the company wants to achieve a growth rate of at least 15% without changing its capital structure or issuing new equity, the maximum dividend payout ratio for the company would be closest to:（）

A. 0.0%.

B. 12.5%.

C. 40.0%.
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