伽利略在研究物体在无阻力的下落运动(即自由落体运动)时,曾让不同质量的铜球沿阻力

题型:选择题

问题:

伽利略在研究物体在无阻力的下落运动(即自由落体运动)时,曾让不同质量的铜球沿阻力极小的斜面滚下,结果发现铜球的下滑加速度都是相同的.不断增大斜面倾角,结果发现,只是铜球的下滑加速度增大了,而所有铜球的下滑加速度仍是相同的,由此他推知(  )

A.自由落体运动应该是匀加速直线运动,但不同质量的铜球下落的加速度可能不同

B.自由落体运动应该是匀加速直线运动,且不同质量的铜球下落的加速度是相同的

C.即使物体在水中自由下落,所有物体下落的加速度也应该是相同的

D.即使物体在油中自由下落,所有物体下落的加速度也应该是相同的

考点:匀变速直线运动的位移与时间的关系伽利略对自由落体运动的研究
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8253DMA本身有16位的地址寄存器和字节计数器,若欲在内存容量为128MB的 PC机内按字节进行DMA数据传送,则附加的页面地址寄存器应用( )

A.8位

B.10位

C.11位

D.12位

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At one time, computers were expected largely to remove the need for paper copies of documents(文件)because they could be stored electronically. But for all the texts that are written, stored and sent electronically, a lot of them are still ending up on paper.

It is difficult to measure the quantity of paper used as a result of Internet-connected computers, although just about anyone who works in an office can tell you that when e-mail is introduced, the printers start working overtime. “I feel in my bones this revolution is causing more trees to be cut down,” says Ted Smith of the Earth Village Organisation.

Perhaps the best sign of how computer and Internet use pushes up demand for paper comes from the high-tech industry itself, which sees printing as one of its most promising new markets. Several Internet companies have been set up to help small businesses print quality documents from a computer. Earlier this week Hewlett-Packard Co. announced a plan to develop new technologies that will enable people to print even more so they can get a hard copy of a business document, a medical record or just a one-line e-mail, even if they are nowhere near a computer. As the company sees it, the more use of the Internet the greater demand for printers

Does all this mean environmental concerns (环境问题) have been forgotten? Some activists suggest people have been led to believe that a lot of dangers to the environment have gone away. “I guess people believe that the problem is taken care of, because of recycling (回收利用),”said Kelly Quirke, director of the Rainforest Action Network in San Francisco. Yet Quirke is hopeful that high-tech may also prove helpful. He says printers that print on both sides are growing in popularity. The action group has also found acceptable paper made from materials other than wood, such as agricultural waste.

72.   The growing demand for paper in recent years is largely due to ___________.

A.    the rapid development of small businesses    B. the opening up of new markets

C.    the printing of high quality copies               D. the increased use of the Internet

73.   Environmentalists believe one possible way of dealing with the paper situation is ______.

A.    to encourage printing more quality documents

B.    to develop new printers using recycled paper

C.    to find new materials for making paper

D.    to plant more fast-growing trees

74.   Hewlett-Packard Co. has decided to develop new technologies because ___________.

A.    people are concerned about the environment

B.    printers in many offices are working overtime

C.    small companies need more hard copies

D.    they see a growing market for printers

75.   What would be the best title for the text?

A. Computers and Printers                                B. E-mail and the Business World

C. Internet Revolution and Environment                D. Modern Technology and New Markets

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以农户联保方式发放的农村个人生产经营贷款,单户贷款额度最高不得高于()万元。

A.10

B.20

C.30

D.60

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性连锁是()年,由()发现的。

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晚清世界历史教育教科书《万国历史》,有意删减或修改了原著中的某些词句,如将“以固人民之自由及平等之权利”删掉、将“法兰西革命”改为“法兰西变乱”、“革命时代”改为“旧学改革时代”等。晚晴政府这样做的主要目的是()

A、促使更多的人了解世界

B、压制资产阶级革命运动

C、宣传救亡图存爱国理念

D、探索西方国家富强奥秘

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