题目内容
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A bottle weighs less after air is taken out, ______proves that air has weight.
A．we
B．it
C．which
D．what
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更多“A bottle weighs less after air…”相关的问题
A. an equal amount of silver
B. an equal amount of gold
C. all the water in the jar now
D. the water that leaves the jar
Archimedes is most well-known for one specific idea that he came up with. "Archimede's Principle" states that a solid object which is immersed in a liquid is pushed up by a force which is equal to the weight of the water that the object moves. For example, if you put a piece of wood and a piece of gold the same size in water, only the wood will float. Both the wood and gold move the same amount of water, but the wood weighs less than this water, while the gold weighs more.
It is believed that Archimedes discovered this principle when the king of Syracuse asked him to solve a problem. The king wanted to know if his crown was pure gold or a mixture of gold and silver. The king, of course, did not melt his crown to find out. The idea came to Archimedes as he lowered himself into his bath. He noticed how the water spilled out of the tub. He decided to use the same idea for the crown. He knew that a gold crown immersed in water would weigh more than one made of silver. The experiment was done and the goldsmith was proved guilty of trying to cheat the king.
A good title for the selection is ______.
A．Archimedes
B．Archimedes' Principle
C．A gold and silver crown
D．The king of Syracuse
Suppose a man wanted to reach a distant star. Even if he traveled his whole life, he would have to move faster than the speed of the light. Nothing can move that fast except light itself.
Strange things happen to an object when it moves rapidly. The object weighs more. An object moving at 86 percent of the speed of light is twice as heavy as it is at rest. A stick appears shorter. A clock runs more slowly. A man would not age so fast as he would on the earth.
Light travels more than 186,000 miles a second, or about 11 million miles a minute. In one year, light travels six trillion miles. That great distance is called a light-year. It is used to measure distance in space.
The star closest to our sun is Alpha Centauri. It is more than four light-years away. If one traveled at the speed of light, he could make a round trip to Alpha Centauri in nine years. But, even at that speed, he could not reach Alcaid (北斗星) in the handle of the Big Dipper. A one-way journey to Alcaid would take almost 200 years
1．In this passage the words “closest to our sun” means the star（）.
A、the earth we live on
B、Alpha Centauri
C、the Big Dipper
D、the moon
2．A one-way journey to Alcaid would take（）.
A、about nine years
B、less than four years
C、almost 200 years
D、less than 100 years
3．Why do we measure the distance in light-years instead of miles?（）
A、Units of light-years sound better.
B、Using light- years reduced the number of figures used.
C、We used to measure distance in light-years long ago.
D、We do not make mistakes when we use light-years.
4．If a stone moved at the speed of light, it（）.
A、would weigh twice more than it is motionless
B、would weigh as much as it is on earth
C、would weigh less than it is on earth
D、would not have weight at all
5．This story is mainly about （）.
A、the distance between the sun and the other stars
B、the problems of traveling to faraway stars
C、what happens when we travel faster than the speed of light
D、the tool we use when we go to faraway stars
Milk was one of the main foods for people long before history was written. Maybe【21】will remain an important food as long as there are【22】that give milk. The old word "milk"【23】Sanskrit(梵文), one of the oldest【24】known to man. A very old picture of milking,【25】was drawn five thousand years ago, has been found.
In the years long ago, people got their milk【26】their own animals. But【27】modern times new inventions made the milk industry(产业) a big business.【28】1851 Gall Borden found a way to【29】some of the water out from milk. This made milk keep longer. Four years later, Louis Pasteur【30】 a way to kill the bacteria(细菌) in milk. Then a special milk bottle was made. This was followed【31】 the invention of machines that could fill bottles with milk. The discoveries had a great effect(影响) on the milk industry. They meant that milk could be kept longer.
Some people believe that milk drinking will become less popular【32】 it has been. But remember how long milk has been an important food【33】 think of the many ways【34】 it is useful. It seems【35】 to say that the milk industry will always be important.
(36)
A．it
B．they
C．he
D．she
The manufacturer who increases the unit price of his product by changing his package size to lower the quantity delivered can, without undue hardship, put his product into boxes, hags, and tins that will contain even 4-ounce, 8 ounce, one-pound, two-pound quantities of break fast foods, cake mixes, etc. A study of drugstore and supermarket shelves will convince any observer that all possible sizes and shapes of boxes, jars, bottles, and tins are in use at the same time, and, as the package journals show, week by week, there is never any hesitation in introducing a new size and shape of box or bottle when it aids in product differentiation. The producers of packaged products argue strongly against changing sizes of packages to contain even weights and volumes, but no one in the trade comments unfavorably on the huge costs incurred by end less changes of package sizes, materials, shape, art work, and net weights that are used for improving a product's market position.
When a packaging expert explained that he was able to multiply the price of hard sweets by 2.5, from $ 1 to $2.50 by changing to a fancy jar, or that he had made a 5-ounce bottle look as though it held 8 ounces, he was in effect telling the public that packaging can be a very ex pensive luxury, h evidently does come high, when an average family pays about $ 200 a year for bottles, cans, boxes, jars and other containers, most of which can't be used for anything but stuffing the garbage can.
What started the public and Congressional concern about deceptive packaging rumpus'？
A．Consumers' complaints about the changes in package size.
B．Expensive packaging for poor quality products.
C．A senator's discovery of the tricks in packaging.
D．The rise in the unit price for many products.
此题为判断题(对，错)。
