试题与答案

在探究“平面镜成像的特点”时,为便于找到虚像的位置,需采用______作为平面镜

题型:问答题

题目:

在探究“平面镜成像的特点”时,为便于找到虚像的位置,需采用______作为平面镜.确认虚像的位置时,要求移动未点燃的蜡烛,直到从镜前的______看去,它都好像点燃似的.研究成像的虚实情况,应在像的位置放置______,并观察其是否有像存在.实验中,要比较像与物的大小、像与物到镜面的______,以及物像连线与镜面的夹角关系.

答案:

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Here They Come


Most of the immigrants came because they were hungry—hungry for more bread and for better bread. America offered that. Europe was old; America was young. European soil had been farmed for many years; American soil was practically untouched. In Europe the land was in the hands of a few people, the upper classes; in America the land was available to all. In Europe it was difficult to get work; in America it was easy to get work. In Europe there were too many laborers looking for the few available jobs, so wages were low; in America there weren’t enough laborers to fill the available jobs, so wages were high.
A bigger and better loaf of bread, then, attracted most of the inpouring hordes of people to America. But many came for other reasons. One was religious persecution. If you were a Catholic in a Protestant country, or a Protestant in another kind of Protestant country, or a Jew in almost any country, you were oftentimes made very uncomfortable, You might have difficulty in getting a job, or you might be laughed at, or have stones thrown at you, or you might even be murdered — just for having the wrong (that is, different) religion. You learned about America where your religion didn’t make so much difference, where you could be what you pleased, where there was room for Catholic, Protestant, Jew. To America, then!
Or perhaps you had the right religion but the wrong politics. Perhaps you thought a few people in your country had too much power, or that there should be no kings, or that the poor people paid too much taxes, or that the masses of people should have more to say about governing the country. Then, oftentimes, your government thought you were too radical and tried to get hold of you to put you into prison, where your ideas might not upset the people. You didn’t want to go to prison, so you had to leave the country to avoid being caught. Where to go under the circumstances Some place where you could be a free man, where you weren’t clapped into jail for talking. Probably you turned to the place Joseph described in his letter to his brother. "Michael, this is a glorious country; you have liberty to do as you will. You can read what you wish, and write what you like, and talk as you have a mind to, and no one arrests you. " Off to America!
For several hundred years America was advertised just as Lucky Strike cigarettes and Buick ears are advertised today. The wonders of America were told in books, pamphlets, newspapers, pictures, posters—and always this advice was given," Come to America. " But why should anyone be interested in whether or not Patrick McCarthy or Hans Knobloch moved from his European home to America There were two groups interested at different times, but for the same reason — business profits.
In the very beginning, over three hundred years ago, trading companies were organized which got huge tracts of land in America for nothing or almost nothing. That land, however, was valueless until people lived on it, until crops were produced, or animals killed for their furs. Then the trading company would step in, buy things from the settlers and sell things to company would step in, buy things from the settlers and sell things to them — at a profits. The Dutch West India Company, the London Company, and several others were trading companies that gave away land in America with the idea of eventually making money on cargoes from the colonists. They wanted profits — needed immigrants to get them — advertised — and people came.
In later years, from 1870 on, other groups interested in business profits tried to get people to come to America. The Cunard line, the White Star line, the North German Lloyed, and several others earned money only when people used their ships. They therefore sent advertisements to all parts of the world to get people to travel to America — in their ships. They sent not only advertisements, but also agents whose business it was to "hunt up emigrants. " All the other reasons mentioned before were operating, and along came a man who promised to help you, gave you complete directions, aided you in all the little details that were necessary, sometimes even got you a passport, and finally led you to the right ship — To America !
For one reason or another, then, people were attracted to America and came of their own free will. There were others who came not because they wanted to, but because they had to.
In the early days when America was a colony of England, that country saw a chance to get rid of people who seemed to be "undesirable". Accordingly, hundreds of paupers and convicts were put on ships and sent to America. Some of the latter were real criminals, but many had been put in prison for small offenses such as poaching, or stealing a loaf of bread, or being in debt. However, they were not "good citizens" as far as English was concerned, so what better idea could that country have than to get rid of them Off to America, whether they liked it or not!
There were two groups of indentured servants. There were those who voluntarily sold themselves for a four-to-seven-year term just to get their passage paid. There was another group, however, "who were carried here against their will — hustled on board ships, borne across the sea and sold into bondage. The streets of London were full of Kidnappers — "spirits," as they were called; no workingman was safe; the very beggars were afraid to speak with anyone who mentioned the terrifying word America. Parents were torn from their homes, husbands from their wives, to disappear forever as if swallowed up in death. Children were bought from worthless fathers, orphans from their guardians, dependent or undesirable relatives from families weary of supporting them. "
Still another group of immigrants were brought against their will. When the early settlers found it practically impossible to make good slaves of the Indians they found here, because the red man was too proud to work under the lash, they turned to Africa, where Negroes could be obtained. For most of the eighteenth century over twenty thousand slaves were transported every year. Negro slave trading became a very profitable business. Many great English fortunes were founded on the slave trade. The Gladstone family fortune is a famous example.
As might be expected, the privations suffered by the whites in the sea crossing were nothing when compared to the misery of the Negroes. Here is a sample account of conditions on the slave ships:
"She had taken in, on the coast of Africa, 336 males, and 226 females, making in all 562, and had been out seventeen days, during which she had thrown overboard 55. The slaves were all enclosed under grated hatchways, between decks. The space was so low that they sat between each other’s legs, and stowed so close together that there was no possibility of their lying down, or at all changing their position, by night or day. Over the hatchway stood a ferocious-looking fellow, with twisted thongs in his hand, who was the slave-driver of the ships, and whenever he heard the slightest noise below, he shook the whips over them.
But the circumstance which struck us most forcibly was, how it was possible for such a number of human beings to exist, packed up and wedged together as tight as they could cram, in low cells, three feet high, the greater part of which, except that immediately under the grated hatchways was shut out from light or air, and this when the thermometer, exposed to the open sky, was standing in the shade, on our deck at 89 degrees.
It was not surprising that they should have endured much sickness and loss of life in their Short passage. They had sailed from the coast of Africa on the 7th of May, and had been out but seventeen days, and they had thrown overboard no less than fifty-five, who had died of dysentery and other complaints, in that space of time, though they had left the coast in good health. Indeed, many of the survivors were seen lying about the decks in the last stage of emaciation, and in a state of filth and misery not to be looked at. "
And so they came, both the willing and the unwilling.

Some ______ who were real criminals were put in prison for small offenses.

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