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（新华社杭州2013年3月19日电）我国浙江大学的科学家们研制出了一种超轻气凝胶--“全碳气凝胶”，刷新了目前世界上最轻材料的记录．

（1）其内部由碳纳米管和石墨烯共同支撑起无数个孔隙，充斥着空气，因此极为轻盈，密度仅为0.16mg/cm3，为______g/cm3．

（2）如图所示，由气凝胶制成约8cm3的“碳海绵”亭亭玉立地静止在桃花的花蕊上，那么该“气凝胶”的质量为______g．

答案

（1）0.16mg/cm3=0.16×1mg/cm3=1.6×10-4g/cm3．

（2）由ρ=

m
V
得，

该“气凝胶”的质量为m=ρV=1.6×10-4g/cm3×8cm3=1.28×10-3g．

故答案为：（1）1.6×10-4；1.28×10-3g．

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Part 3


Questions 19-25


·Read the following passage and answer questions 19-25.
·For questions 19-25, choose the correct answer from A, B, C and D.
·Mark your answer on the Answer Sheet.
The number of speakers of English in Shakespeare’s time is estimated to have been about five million. Today it is estimated that some 260 million people speak it as a native language. Mainly in the United States, Canada, Great Brittany, Ireland, South African, Australia and New Zealand. In addition to the varieties of English found in these areas, there are great many regional and social varieties of the language, as well as various levels of usage that are employed both in its spoken and written forms.
It is virtually possible to estimate the number of people in the world who acquired adequate work knowledge of English in addition to their own languages. The purpose for which English is learned and the situation in which such learning takes place are so varied that it is difficult to define and still more difficult to assess what constitutes an adequate working knowledge for each situation.
The main reason for the widespread demand for English is its present-day importance as a world language. Besides serving the infinite needs of its native speakers, English is a language in which some of the most important works in science, technology, and other fields are produced and not always by native speakers. It is widely used for such purpose as meteorological and airport communications, international conferences, and the spread information over the radio and television networks of many nations for the number of developing countries, especially former British colonies. Many of these countries have multi-lingual populations and need a language for internal communication as well as for international communication and for access to the scientific and technological development in the west.

An appropriate title for this passage would be ______.

A．English as a World Language

B．International Communications

C．The Difficulty of Learning English

D．The Standard Variety of English
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单项选择题

血站对献血者每次采集血液量一般为200毫升，最多不得超过400毫升，两次采集间隔期不得少于

A．3个月
B．4个月
C．5个月
D．6个月
E．7个月
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