We are so used to our life on the surface of the earth that it can be quite an effort for our mind to break free of all the ideas that we take for granted. Because we can feel that things are heavy, we think of "weight" as being a fixed quality in an object, but it is not really fixed at all. If you could take a one-pound packet of butter 4,000 miles out from the earth, it would weigh only a quarter of a pound.
Why would things weigh only a quarter as much as they do at the surface of the earth if we took them 4,000 miles out into space The reason is this: All objects have a natural attraction for all other objects; this is called gravitational attraction. But this power of attraction between two objects gets weaker as they get farther apart. When the butter was at the surface of the earth, it was 4,000 miles from the center. When we took the butter 4,000 miles out, it was 8,000 f
A. it is fixed if it is outside the earth’s gravitational pull
B. it decreases four times when it is 4,000 miles from the earth’s center
C. it varies with the change of the gravitational attraction between two objects
D. things increase in amount as they are closer to the earth’s surface
We are so used to our life on the surface of the earth that it can be quite an effort for our mind to break free of all the ideas that we take for granted. Because we can feel that things are heavy, we think of "weight" as being a fixed quality in an object, but it is not really fixed at all. If you could take a one-pound packet of butter 4,000 miles out from the earth, it would weigh only a quarter of a pound.
Why would things weigh only a quarter as much as they do at the surface of the earth if we took them 4,000 miles out into space The reason is this: All objects have a natural attraction for all other objects; this is called gravitational attraction. But this power of attraction between two objects gets weaker as they get farther apart. When the butter was at the surface of the earth, it was 4,000 miles from the center. When we took the butter 4,000 miles out, it was 8,000 f
A. 1 pound.
B. 2 pounds.
C. 3 pounds.
D. 4 pounds.
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Types of risks So far we have used the term "risk" rather loosely. One type of risk is default risk, that is, the risk that the borrower will simply not repay the loan, due to either dishonesty or plain inability to do so. Another type of risk, called purchasing - power risk, is the risk that, due to an unexpectedly high inflation rate, the future interest payments, and the principal of the loan when finally repaid, will have less purchasing power than the lender anticipated at the time the loan was made. A similar risk is faced by borrowers. A borrower may cheerfully agree to pay, say, 15 percent interest, expecting that a 12 percent inflation rate will reduce the real value of the loan. But inflation may be only 4 percent. A third type of risk is called "interest - rate risk" or "market risk", tha A. The existence of inflation produces purchasing - power risk. B. Purchasing - power risk involves a loss in the value of money loaned or borrowed be- cause of higher or lower inflation than expected. C. Purchasing - power risk produced by an inflation higher than expected affects lenders only. [填空题]Traveling used to be so expensive that many middle-class people could not afford it.
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When a speetrophotometer is used,we should pay attention to the influence of solvent on absorbance．The solvent in the reference cell should be（） A. provided by the same manufactory B. produced in the same city C. in the same size D. in the same concentration E. of the same batch [单项选择]
It used to be so straightforward. A team of researchers working together in the laboratory would submit the results of their research to a journal. A journal editor would then remove the authors’ names and affiliations from the paper and send it to their peers for review. Depending on the comments received, the editor would accept the paper for publication or decline it. Copyright rested with the journal publisher, and researchers seeking knowledge of the results would have to subscribe to the journal. [单项选择]
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