制作显微镜观察的标本材料往往很薄，其原因是（）A.薄利于透光 B.薄利于染色 C.薄 发布时间：2017-10-09 00:32 │ 来源：www.tikuol.com 题型：单项选择题 问题： 制作显微镜观察的标本材料往往很薄，其原因是（）A.薄利于透光B.薄利于染色C.薄利于节省材料D.薄利于用盖玻片
题型：单项选择题 完形填空。 when Chinese people find out that someone comes from London, they often say, "London is a foggy city, isn't it?" British people who visit China often 1 say that London is not a foggy city at all!But if London is not foggy. 2 bo so many people in China think it is?In tact, London used to be a foggy city, 3 in isn't any more. In London peole of this it in pollution (污染) came from factories, but a lot of it came from coal (煤)because people used it in their houses 4 warm duing the winter.By the 1950s, Long-don's air pollution had became so 5 that the govemment (政府) decided to do something to clean up the air. A new rule was made. It said that 6 was not allowed to bum (燃烧) cosl in any British city. Just a few years 7 , the air became much cleaner. Now many Chinese cities meet the same kind of 8 with air pollution that London met forty or fitty years ago. However.this problem is more difficult for Chinese cities to 9 . First, more of the pollution comes from big fsctoies than from coal that pcople use in their houses. If these fac-lories are suddenly closed, lots of people 10 their jobs.Second, cleaner fuels(燃料)are quite expensive. However, the air in many cities is 11 slowly becoming cleaner,because the govem-ment and ordinary people are trying to make pollution 12 . As a result,the air in Beijing is get-ting cleaner and cleaner. ( )1. A. must ( )2. A. what ( )3. A. and ( )4. A. to keep ( )5. A. well ( )6. A. somebody ( )7. A. before ( )8. A. problem ( )9. A. find ( )10. A. lost ( )11. A. almost ( )12. A. liule B. have to B. when B. but B. keeping B. good B. anybody B. ago B. questionB. answer B. lose B. already B. less C. should C. which C. SO C. kept C. badly C. nobody C. later C. accident C. solve C. would lose C. hardly C. much D. Will D. why D. or D. keep D. bad D. everybody D. after D. discussion D. save D. will lose D. nearly D. more 查看答案
题型：单项选择题 不定项选择如图所示，1、2、3、4为玻尔理论中氢原子最低的四个能级。用以下能量的光子照射基态的氢原子时，能使氢原子跃迁到激发态的是（ ） A．1.51eV B．3.4eVC．10.2eVD．10.3eV 查看答案
