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【单选题】
In this part of the Reading section, you will read 2 passages. You will have 40 minutes to read the passages and answer the questions. Most questions in the Reading section are worth 1 point, but the last question for each passage is worth more than 1 point. The directions for the last question include the point value of the question. Some passages will include a word or phrase that is underlined in blue. Click on the word or phrase to see its definition or an explanation. Within each part, you can go on to the next question by clicking the Next icon. You may skip questions and go back to them later. If you want to go back to previous questions, click the Back icon. You may click the Review icon at any time and the review screen will show you which questions you have answered and which you have not. From the review screen, you can go directly to any question you have already seen in the Reading section. Click Continue to go on. Clipper Ships Clipper ships are small, lightweight vessels with three masts that boast a massive array of sails which allow them to move extremely quickly. The name 'clipper' is thought to come from the fact that the bow of such a ship seems to cut through water as it advances, something also true of older types of ship. Certainly, people were using the expression 'to go at a good clip' to mean 'to travel quickly' long before the advent of the clipper ship, so the explanation seems to make sense. In fact, it is difficult to date the emergence of the first true clipper, since the word was liberally applied to several speedy ships from the early 19th century that did not possess the technical specifications to qualify as clippers under the later definition of the term. What is known, however, is that by the 1840s, several shipyards were engaged in building vessels that were recognizably clipper ships. The great advantage of the clipper ship was its speed. A decently built clipper ship could routinely cover 250 miles per day, and with good winds, would often travel much faster, in some cases surpassing 400 miles per day. This made the clipper ideal for transporting people from one place to another, since prolonged sea voyages at that time were unpleasant and risky. The clippers were also used to transport freight, but in a more limited fashion, since clippers had considerably less cargo space than ordinary freighters of the time. (A) This meant that it was often cheaper to transport durable goods, such as furniture and jewelry, on regular ships that could carry a greater amount of cargo, even if it took longer for that cargo to reach its destination. (B) However, for perishable goods, such as spices and teas which would lose their potency over time, clippers proved an immensely profitable method of transport. (C) Clippers were also pressed into service in situations where time was viewed as more valuable than money. This was the case at the time of the California gold rush, when gold-crazed individuals were determined to be the first to reach what they hoped would be prime prospecting locations. (D) The clipper ship was also used for less respectable activities. Because its great speed meant that it could outrun or overtake virtually any other type of seafaring vessel known at the time, clippers became the ships of choice for pirates and smugglers. Pirates would use clippers to chase down slower, heavier freighters, then board their victims, transfer the most valuable pieces of cargo to the clipper, and make a speedy getaway before the authorities could get there. Smugglers could more easily conceal small clippers from prying eyes than they could large sloops, and if discovered, they had a much greater chance of successfully fleeing pursuit. This in turn forced coastal and military authorities to make use of clipper ships as well, simply to keep up with the criminal element. As a result, clippers also became favorites of maritime authorities and privateers. The term 'privateers' refers to those who crewed ships that were legally entitled by their governments to attack vessels in the service of foreign powers with whom those governments were at war. Unfortunately, privateers operated essentially unsupervised, and it was not uncommon for clippers initially commissioned to guard the seas to turn pirate if the Crew saw an opportunity for a quick profit. The era of the clipper was fairly short-lived. Clippers began being built just before the advent of steam-powered boats. These steam-powered boats quickly replaced clippers as the vessels of choice for traders, not because they were faster, since they initially werent, but because they were much more reliable. A clipper, fast as it was, could only make good time with the wind behind it. Headwinds would slow it considerably, and no wind at all would leave it helplessly adrift. A steam boat would often take longer to reach its destination than a clipper would have done, but reach its destination it would, regardless of the strength and direction of the prevailing winds. The opening of the Suez Canal in 1869 was the final nail in the coffin of commercial clippers, since only steamboats could easily navigate the canal, which shaved thousands of miles off of the journey between Europe and Asia. In addition, clipper ships were notoriously short-lasting vessels, and most were junked well before reaching twenty years of service, much sooner than the average steamboat. For all of these reasons, by the turn of the 20th century, clipper production had all but ceased. The word 'firmament' in the passage is closest in meaning to
A.
earth.
B.
stars.
C.
sky.
D.
clouds.
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【多选题】以下正确的if语句形式是
A.
if(x>y&&x!=y)
B.
if(x==y)x+=y
C.
if(x
【简答题】设X 1 ,X 2 ,X 3 相互独立.且X 1 ~U[0,6],X 2 ~N(0,4),X 3 ~P(2),Y=X 1 -2X 2 +3X 3 ,求EY及DY.
【单选题】William Faulkner was the writer of .
A.
Walden
B.
Uncle Tom's Cabin
C.
The Sound and the Fury
D.
Moby Dick
【简答题】(1) 设随机变量X 1 ,X 2 ,X 3 相互独立,且有 ,求P{X 1 =2,X 2 =2,X 3 =5),E(X 1 X 2 X 3 ),E(X 1 -X 2 ),E(X 1 -2X 2 ). (2) 设X,Y是随机变量,且有E(X)=3,E(Y)=1,D(X)=4,D(Y)=9,令Z=5X-Y+15,分别在下列3种情况下求E(Z)和D(Z). (i) X,Y相互独立,(ii)X,Y不相关...
【判断题】The writer of Walden is Henry David Thoreau.()
A.
正确
B.
错误
【简答题】The writer has a high opinion of Thoreau's living all by himself at Walden Pond.
【判断题】The writer of Walden is Henry David Thoreau.
A.
正确
B.
错误
【简答题】设X~N(3,2 2 ),(1)求P{2<X≤5),P{-4<X≤10),P{|X|>2),P{X>3);(2)确定c使得P{X>c}=P{X≤c};(3)设d满足P{X>d}≥0.9,问d至多是多少?
【单选题】德国狂飙突进运动的灵魂人物是
A.
康德
B.
黑格尔
C.
歌德
D.
雨果
【单选题】第二类防雷建筑物,当仅利用建筑四周的钢柱或柱子钢筋作为引下线时,可按跨度设引下线,引下线的平均间距不应大于( )。
A.
10m
B.
12m
C.
15m
D.
18m
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