题目

下列各种应用与其涉及的主要物理知识，错误的是（   ） A . 船闸﹣﹣利用连通器原理 B . 活塞式抽水机﹣﹣利用大气压强作用 C . 拦河大坝上窄下宽﹣﹣液体压强随深度增加而增大 D . 飞机机翼做成上表面凸起，下表面平直﹣﹣利用空气的浮力 答案：DIt was once common to regard Britain as a society with class distinction. Each class had unique characteristics.In recent years, many writers have begun to speak the ‘decline of class’ and ‘classless society’ in Britain. And in modern day consumer society everyone is considered to be middle class.But pronouncing the death of class is too early. A recent wide-ranging society of public opinion found 90 percent of people still placing themselves in particular class; 73 percent agreed that class was still a vital part of British society; and 52 percent thought there were still sharp class differences. Thus, class may not be culturally and politically obvious, yet it remains an important part of British society. Britain seems to have a love of stratification.One unchanging aspect of a British person's class position is accent. The words a person speaks tell her or his class. A study of British accents during 1970s found that a voice sounding like a BBC newsreader was viewed as the most attractive voice. Most people said this accent sounded ‘educated’ and ‘soft’. The accents placed at the bottom in this study, on the other hand, were regional（地区的）city accents. These accents were seen as ‘common’ and ‘ugly’. However, a similar study of British accents in the US turned these results upside down and placed some regional accents as the most attractive and BBC English as the least. This suggests that British attitudes towards accent have deep roots and are based on class prejudice.In recent years, however, young upper middle-class people in London, have begun to adopt some regional accents, in order to hide their class origins. This is an indication of class becoming unnoticed. However, the 1995 pop song ‘Common People’ puts forward the view that though a middle-class person may ‘want to live like common people' they can never appreciate the reality of a working-class life.1.A recent study of public opinion shows that in modern Britain ________. A. it is time to end class distinctionB. most people belong to middle classC. it is easy to recognize a person’s classD. people regard themselves socially different2.The word stratification in Paragraph 3 is closest in meaning to ________.A. variety B. division C. authority D. qualification3.British attitudes towards accent _________.A. have a long traditionB. are based on regional statusC. are shared by the AmericansD. have changed in recent years4.What is the main idea of the passage?A. The middle class is expandingB. A person’s accent reflects his classC. Class is a key part of British societyD. Each class has unique characteristics.