练习题一

练习题一

Paper One

Part I Reading Comprehension

Directions: There are several passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A), B), C) and D). You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the centre.

Passage One

Questions 1 to 5 are based on the following passage:

Supermarkets are trying to cheat you to spend more. For example, moving a brand from the bottom shelf to eye level can increase sales by 50 percent. It’s no surprise, then, that foods and other high-profit items are at eye level. To beat supermarkets at their own game, use coupons (优惠券), buy in quantity and shop with your eyes open.

We gave a same shopping list to two staff members, asking one to choose items regardless of cost and the other to look for low prices. Our impulsive shopper would come up with name-brand products costing $110.05. The careful shopper’s cart contained mostly store brands. She spent $59.35, a saving of $50.70.

Usually our careful shopper did not have to settle for lower quality. In the past tests, many store-brand products (tea bags, peanut butter, preserves, glass cleaner) have done as well as or better than name-brand (名牌) ones. Shopping the way our careful staffer did, you would be able to save $2,500 a year buying for a family of four.

Sometimes, brand-name items are of better quality. sometime’s they’re more convenient. Nonetheless, we promise you: if you shop with your eyes open, you’ll save money.

1. One trick used by supermarkets is ________.

A) putting high-profit items usually in the upper-middle place of the shelf

B) use something to attract shoppers’ attention

C) give out coupons to people

D) prohibit quantity buying

2. An “impulsive shopper” ________.

A) makes quick decision as to what to buy and what not to buy

B) often buys something that is useless or he actually doesn’t need

C) always buy those expensive things

D) always buy those cheap things

3. What can be inferred from the passage?

A) Brand-name products are too expensive.

B) Making a shopping list before going shopping is a good way to save money.

C) Store-brand products can be as good as name-brand ones.

D) Buying brand-name products is a waste of money.

4. According to the passage, in the past, some tests had been done on ________.

A) how to save money

B) how a careful shopper behaves

C) why impulsive shopper spends more money

D) the comparison between name-brand products and store-brand ones

5. “Sometimes they’re more convenient” means “________”.

A) sometimes the producers provide convenient services

B) sometimes they are easier to get from the shelf

C) sometimes they are easier to carry and use

D) sometimes they are of better quality

Passage Two

Questions 6 to 10 are based on the following passage:

American this year will swallow 15,000 tons of aspirin, one of the safest and most effective drugs invented by man. The most popular medicine in the world today, it is an effective pain reliever. Its bad effects are relatively mild, and it is cheap.

For millions of people suffering from arthritis (关节炎), it is the only thing that works. Aspirin, in short, is truly the 20th-century wonder drug. It is also the second largest suicide drug and is the leading cause of poisoning among children. It has side effects that although relatively mild are largely unrecognized among users.

Although aspirin was first sold by a German company in 1899, it has been around much longer than that. Hippocrates, in ancient Greece, understood the medical value of the leaves and tree bark which today are known to contain salicylates, the chemical in aspirin. During the 19th century, there was a great deal of experimentation in Europe with this chemical, and it led to the introduction of aspirin. By 1915, aspirin tablets were available in the United States.

A small quantity of aspirin (two five-grain tablets) relieves pain and inflammation (发炎). It also reduces fever by interfering with some of the body’s reactions. Specifica lly, aspirin seems to slow down the formation of the acids involved in pain and the complex chemical reactions that cause fever. The chemistry of these acids is not fully understood, but the slowing effect of aspirin is well known.

Aspirin is very irritating to the stomach lining, and many aspirin takers complain about upset stomach. There is a right way and a wrong way to take aspirin. The best way is to chew the tablets before swallowing them with water, but few people can stand the bitter taste. Some people suggest crushing the tablets in milk or orange juice and drinking that.

6. This passage discusses ________.

A) only the good things about aspirin

B) only the bad things about aspirin

C) both the good and bad things about aspirin

D) neither the good things nor the bad things about aspirin

7. The information in Para. 2 shows that ________.

A) aspirin can be dangerous

B) aspirin is always safe

C) aspirin has been around a long time

D) aspirin is very cheap

8. In Para. 3, the word “salicylates” means “________”.

A) leaves and tree bark

B) the chemical in aspirin

C) aspirin tablets

D) the name of a German company

9. The author of this article seems to be ________.

A) in favor of aspirin

B) against the use of aspirin

C) not interested in aspirin

D) experienced in how to take aspirin

10. A good title for this passage would be ________.

A) The Side Effects of Aspirin

B) Why I Take Aspirin

C) Aspirin: The Most Popular Medicine in the World

D) The Commercial Value of Aspirin

Passage Three

Questions 11 to 15 are based on the following passage:

A mouse engineered at Harvard Medical School has become the first patented (申请了专利的) animal. Born with cancer-promoting genes, the new breed may be invaluable in the study of cancer. But the patent has aroused debate over whether humans have the right to create and own novel life forms.

To create the mice, Philip Leder’s genetics (遗传学) team injected fertilized mouse eggs with hundreds of copies of a cancer gene. Mice that developed from the eggs carried the “oncogene” and passed it to offspring. Thus arouse a breed that is born with breast cancer.

The patent, which covers the creation of any oncogene-carrying mammals (哺乳动物) except humans, has opponents. Ever since 1980 when the Supreme Court ruled that bacteria could be patented, critics have attacked the idea that one species can own another. And because a patent guarantees a monopoly (垄断), critics fear that patenting a laboratory animal may increase costs of research and, finally, new drugs.

Congressional committees are studying the implications, and legislation (立法) is being considered to either prohibit animal patents or impose a two-year term on them. The U. S. Patent and Trademark Office is busy studying too: 21 applications for new animals are coming.

11. “Offspring” in Para. 2 means “________”.

A) other mice

B) other animals

C) the next generation

D) other objects

12. The patented animals are used to ________.

A) create new life forms

B) help humans study some diseases

C) play in movies about animals

D) help disabled people

13. Which of the following statements is NOT true?

A) Patenting a lab animal is harmful to human beings’ life.

B) Critics fear that the act of patenting will deprive the others of doing study on the animal.

C) Patented animals are usually created in laboratories.

D) Patented animals can only be used by their creators.

14. Critics think that ________.

A) patenting a lab animal is meaningless

B) humans don’t have the right to create other species

C) patenting only benefits the individuals

D) humans spend too much money on patented animals

15. Though many people are against the idea of patented animals, ________.

A) the government pays little attention to it

B) the public have no interest in it

C) more patented animals will show up

D) the government can do nothing about it

Passage Four

Questions 16 to 20 are based on the following passage:

Watercolor is the oldest painting medium known. It dates back to the early cave dwellers who discovered they could add lifelike qualities to drawings of animals and other figures on the walls of caves by mixing the natural colors found in the earth with water.

Fresco (壁画), one of the greatest of all art forms, is done with watercolor. It is created by mixing pigments

(颜料) and water and applying these to wet plaster (浆). Of the thousands of people who stand under Michelangelo’s heroic ceiling in the Sistine Chapel (西斯廷教堂), very few are aware that they are looking at perhaps the greatest watercolor painting in the world.

The invention of oil painting by the Flemish masters in the fifteenth century led to a decline in fresco painting, and for the next several centuries watercolor was used mainly as a medium for doing preliminary sketches (速写) or as a tool for study. It was not until the eighteenth and nineteenth centuries that English painters reinstated watercolor as a serious art form. The English have a notorious love for the outdoors and also great fondness for small, intimate pictures. Watercolor had a remarkably strong appeal for them.

The popularity of watercolor continued to grow until in the twentieth century the United states passed England as the center for watercolor, producing such well-known watercolor artists as Thoms Eakins and Andrew Wyeth.

16. What is the main theme of the passage?

A) The decline of fresco painting.

B) The predominance of oils over watercolor.

C) The rediscovery of watercolor in England.

D) The origins and development of watercolor.

17. Who were the first watercolor artists?

A) Early cave dwellers.

B) Italian fresco artists.

C) Flemish masters.

D) English artists of the 18th century.

18. Where did the first colors for painting come from?

A) Animal skins.

B) The ground.

C) Trees and leaves.

D) Caves.

19. In fresco painting, to what is the paint applied?

A) Canvas.

B) Plaster.

C) Paper.

D) Rock.

20. Which of the following can be inferred about what 16th- and 17th-century artists thought of watercolor painting in comparison to oil painting?

A) Watercolor was more costly, but was better.

B) Oil painting was less permanent, but more vivid.

C) Watercolor was not appropriate for finished works.

D) Oil painting tended to be difficult to use.

Part II Vocabulary and Structure

Directions: There are a number of incomplete sentences in this part. For each sentence there are four choices marked A), B), C) and D). Choose the ONE answer that best completes the sentence. Then mark the corresponding letter on the Answer Sheet with a single line through the centre.

21. I can’t _________ three weeks away from my work.

A) offer B) find out C) afford D) spend

22. I cannot help ________ the picture whenever I look at it.

A) to admire B) not to admire C) not admiring D) admiring

23. This matter is between you and me, and don’t give it________ to anybody.

A) away B) out C) up D) over

24. She commanded that the troops ________ the water.

A) to cross B) crossed C) to be crossed D) cross

25. The small firm ________ against the large enterprise.

A) paved its way B) made its way C) mended its way D) took its way

26. She was not as sweet as she has always been painted in ________ relations.

A) personal B) difficult C) good D) strong

27. Reading her work I ________ admiration for what she had achieved.

A) called on B) assumed C) brought about D) was lost in

28. ________ faces are considered pleasant or unpleasant, and rarely ever neutral.

A) Pale B) Fair C) Blank D) White

29. Students today are writing ________ of poetry.

A) a great many lines C) lots lines

B) quantities of lines D) a large number

30. The explorer told the boys about his ________ in the African forests.

A) excursion B) voyage C) flight D) adventures

31. ________ Mary nor John went to the Grand Theatre.

A) Both B) Neither C) Either D) Have

32. I used weed-killer to ________ the weeds in the garden.

A) cut off B) get rid of C) hold back D) choke up

33. ---”It was him. I saw him take it.” ---”Are you ________ about that?”

A) active B) positive C) determined D) reliable

34. We had to read the book, ________?

A) shouldn’t we B) would we C) mustn’t we D) didn’t we

35. As is known to all, industry is the backbone of national economy. Therefore, it ________ be

emphasized too much.

A) can’t B) mustn’t C) shouldn’t D) oughtn’t

36. We have to get that car fixed ________.

A) no matter it costs how much C) no matter how much costs it

B) no matter how much it costs D) no matter how much does it cost

37. She offered us her burnt cakes and smiled ________.

A) apologetically B) practically C) hopelessly D) generally

38. In Singapore people who _______ litter in the streets will be fined heavily.

A) discard B) disregard C) displace D) dispose

39. The guard stood ________ despite the strong wind and biting coldness.

A) erectly B) erecting C) erected D) erect

40. The Democratic Party must reach out to the people and ________ its message if it is to win the

election.

A) figure out B) take over C) drive home D) throw up

41. Before I knew it, I had spent _________ on the journey as had been planned.

A) twice as much B) twice more C) twice much more D) twice much

42. The young actress was given a ________ part in the new play.

A) least B) little C) simple D) minor

43. The group ________ an interesting report on young people’s responses to advertising.

A) turned up B) turned down C) turned in D) turned out

44. In order to improve our condition, this new scheme must be ________.

A) adopted B) adapted C) adjusted D) admitted

45. The government is trying to do something to ________ better understanding between the two

countries.

A) raise B) promote C) heighten D) increase

46. The bookstore has an ________ collection of Arabic language books.

A) extensive B) spacious C) intensive D) capacious

47. I live on a bus ________ so I can easily get to work.

A) way B) path C) route D) track

48. He is so overweight that he has to ________ into the car.

A) squeeze B) breeze C) crush D) cram

49. I’m tired of you _____ me what to do all the time.

A) tell B) being telling C) telling D) to tell

50. He is an ________ likable guy --- so easy to talk to.

A) instantly B) instinctively C) obviously D) intently

51. Creative writing can be ________of fun.

A) a great deal B) a great number C) a good many D) a great many

52. What she said sounded convincing, but I ________ it to be a lie.

A) doubt B) suspect C) seem D) turn out

53. It was merely ________ chance that he discovered the mistake.

A) in B) on C) from D) by

54. In the smoke and dust and darkness, people ________ to one another grabbing hands and

linking arms, they formed a human chain that made its way down stairwells and corridors and out into the sunlight of an unthinkable day.

A) reaching up B) reaching down C) reaching for D) reaching out

55. John _________ his work as soon as he was out of hospital.

A) resumed B) relieved C) gripped D) dealt

56. ---”Why is the university doing so much building?” ---”The number of students ________ that

there aren’t enough classrooms.”

A) have increased so rapidly C) have increased so rapid

B) has increased so rapid D) has increased so rapidly

57. I didn’t believe ________ he said, ________ annoyed him very much.

A) what...which B) which...what C) that...how D) that...what

58. It’s a very beautiful village where Cindy and Tony live but it’s very ________.

A) out of the way B) on the way C) by the way D) on the way

59. Our company has _________ with several American companies for the past few years in joint

ventures.

A) hesitated B) cooperated C) sponsored D) entertained

60. The Second World War ________ in 1939.

A) broke down B) broke into C) broke out D) broke up

Part III Cloze

Directions: There are a number of blanks in the following passage. For each blank there are four choices marked A), B), C) and D). You should choose the ONE that best fits into the passage. Then mark the corresponding letter on the Answer Sheet with a single line through the centre.

Historians can’t tell us when or where or ?61?the first food was cooked. In earliest ?62? , people had eaten their food ?63?and fire was used only to provide heat and light.

The first primitive cooks were ?64?women, ?65?preparing food and making clothing were considered women’s work. ?66?most of the great chefs (厨师) in history have been men. This might have been because chefs learned ?67?work in the kitchens of rich families ?68?in restaurants and women didn’t often take jobs outside their homes, or it might have been because kitchen equipment was so heavy and difficult to work with ?69?

only strong men could do it. In modern times, great female chefs have become known, and some of the best cook books ?70?by women.

61.A) who B) which C) how D) what

62.A) time B) times C) ages D) period

63.A) uncooked B) being uncooked C) uncooking D) to be uncooked

64.A) probable B) possible C) probably D) likewise

65.A) while B) since C) so that D) unless

66.A) But B) Therefore C) And D) Moreover

67.A) his B) its C) their D) theirs

68.A) as well B) either C) both D) or

69.A) as B) such C) so D) that

70.A) have written B) have been written C) were written D) are written

Princeton, New Jersey, is a small quiet town of family homes, even though it does have a world-famous university. It is not a place ?71?anyone would expect to see ?72?characters on the streets.

?73?day in 1940, a little girl in ?74?saw a funny-looking man ?75?towards her. His white hair was wild and ?76?to be standing straight out. His ?77?were much

too big and seemed to have ?78?pulled on like a blanket ?79?him. He was short, had a big nose and deep-set eyes. He was ?80?looking anywhere. It was ?81?that he was thinking deeply. He almost ?82?into the girl before he ?83?her. He smiled at her, then walked on and went on ?84? . The girl turned around to get ?85?look at the strange old man. She noticed that he was wearing his ?86?slippers.

That night ?87?dinner, the girl told her family about the strange, funny man she had seen. “He was almost ?88? a character out of a fairy story,” she exclaimed. ?89?her surprise, her father put ?90?his knife and fork, looked at her, then said, “My child, remember this: today you saw one of the greatest men in the world.” The “strange character” was Albert Einstein, the world-famous scientist.

71.A) that B) where C) which D) but

72.A) good B) kind C) bad D) strange

73.A) Some B) A C) That D) One

74.A) Princeton B) New Jersey C) street D) town

75.A) go B) coming C) to run D) moved

76.A) was B) liked C) seemed D) going

77.A) ears B) clothes C) hands D) feet

78.A) not B) just C) never D) been

79.A) over B) in C) beside D) under

80.A) always B) then C) sometimes D) not

81.A) clearly B) clear C) he D) there

82.A) went B) knocked C) ran D) thought

83.A) talked B) told C) saw D) greeted

84.A) thinking B) smiling C) looking D) saying

85.A) one B) more C) good D) another

86.A) father’s B) mother’s C) sleeping D) bedroom

87.A) before B) after C) at D) in

88.A) probably B) like C) as D) terribly

89.A) To B) On C) By D) Seeing

90.A) down B) away C) up D) off

Name:_____________ Class:_____________

Student No.:_____________ Score:_____________

Answer Sheet

Part I Reading Comprehension

1._____

2._____

3._____

4._____

5._____

6._____

7._____

8._____

9._____10._____

11._____12._____13._____14._____15._____

16._____17._____18._____19._____20._____

Part II Vocabulary and Structure

21._____22._____23._____24._____25._____

26._____27._____28._____29._____30._____

31._____32._____33._____34._____35._____

36._____37._____38._____39._____40._____

41._____42._____43._____44._____45._____

46._____47._____48._____49._____50._____

51._____52._____53._____54._____55._____

56._____57._____58._____59._____60._____

Part III Cloze

61._____62._____63._____64._____65._____

66._____67._____68._____69._____70._____

71._____72._____73._____74._____75._____

76._____77._____78._____79._____80._____

81._____82._____83._____84._____85._____

86._____87._____88._____89._____90._____

练习题一( 参考答案)

Key

Paper One

Part I Reading Comprehension

1.A

2.B

3.B

4.D

5.B

6.C

7.A

8.B

9.A10.C

11.C12.B13.A14.B15.C

16.D17.A18.B19.B20.C

Part II Vocabulary and Structure

21.C22.D23.A24.D25.B

26.A27.D28.C29.A30.D

31.B32.B33.B34.D35.A

36.B37.A38.A39.D40.C

41.A42.D43.C44.A45.B

46.A47.C48.A49.C50.A

51.A52.B53.D54.D55.A

56.D57.A58.A59.B60.C

Part III Cloze

61.C62.B63.A64.C65.B

66.A67.C68.D69.D70.B

71.B72.D73.D74.A75.B

76.C77.B78.D79.A80.D

81.B82.C83.C84.A85.D

86.D87.C88.B89.A90.A

新概念第一册练习题大全

新概念第一册练习题答案大全 A About you Copy this dialogue. Add your own name at the end. 抄写这段对话，. 在结尾处加上你的名字。 Sue: Excuse me. ______ John: Yes? ______ Sue: What’s your name? ______ John: Pardon? ______ Sue: What’s your name? ______ John: My name is John. ______ Sue: What’s your name? ______ You: My name is...... ______ B Vocabulary Write the correct words in the questions．. 用正确的词完成以下问句。book car coat dress house√. pen pencil shirt wathc 1 Is this your h______? Is this your c______? Is this your w______? Is this your c______? Is this your sh ______? Is this your d______? Is this your b______? Is this your p______? Is this your p______? 10 Is this your s ______? C Numbers

Write the numbers in figures．. 用阿拉伯数字表示以下数词。 three ten______ one______ four______ six______ five______ eight_________ seven______ two______ nine______ Lesson 1 B watch shirt book pen coat car dress pencil 10 skirtC 10，1，4，6，5，8，7，2，9 新概念英语第一册习题 Lesson Lesson Is this your....？这是你的....吗？ A Structure Write questions with the words．用所给的词写出问句。 Handbag Is this your handbag? 1 book ______ car ______ coat ______ dress ______ house ______ pen ______

1.第一章课后习题及答案

第一章 1.(Q1) What is the difference between a host and an end system List the types of end systems. Is a Web server an end system Answer: There is no difference. Throughout this text, the words “host” and “end system” are used interchangeably. End systems inc lude PCs, workstations, Web servers, mail servers, Internet-connected PDAs, WebTVs, etc. 2.(Q2) The word protocol is often used to describe diplomatic relations. Give an example of a diplomatic protocol. Answer: Suppose Alice, an ambassador of country A wants to invite Bob, an ambassador of country B, over for dinner. Alice doesn’t simply just call Bob on the phone and say, come to our dinner table now”. Instead, she calls Bob and suggests a date and time. Bob may respond by saying he’s not available that particular date, but he is available another date. Alice and Bob continue to send “messages” back and forth until they agree on a date and time. Bob then shows up at the embassy on the agreed date, hopefully not more than 15 minutes before or after the agreed time. Diplomatic protocols also allow for either Alice or Bob to politely cancel the engagement if they have reasonable excuses. 3.(Q3) What is a client program What is a server program Does a server program request and receive services from a client program Answer: A networking program usually has two programs, each running on a different host, communicating with each other. The program that initiates the communication is the client. Typically, the client program requests and receives services from the server program.

物理3-1第一章--习题及测试卷

选修3-1 第一章 静电场 练习 第一节 电荷及其守恒定律 1．带电棒吸引干燥软木屑，木屑接触棒以后，往往又剧烈地跳离此棒。试解释之。 2．1C 相当于多少电子所带的电荷量？ 3．把一个带电棒靠近一个带正电的验电器，金属箔片先闭合而后张开，这说明棒上带的是( ) A ．正电荷 B ．负电荷 C ．正、负电荷都有可能 D ．不带电 4．把两个相同的金属小球接触一下再分开一小段距离，发现两球之间相互排斥，则这两个金属小 球原来的带电情况可能是( ) A ．两球原来带有等量异种电荷 B ．两球原来带有同种电荷 C ．两球原来带有不等量异种电荷 D ．两球中原来只有一个带电 第二节 库仑定律 1．两个电荷量大小相等的点电荷，在真空中相距1 m 时，相互吸引力为0.1N ，则它们的电荷 量分别是Q 1＝______C ，Q 2＝______C 。将它们相碰一下再放到相距1m 远处，它们的相互作用力为______。 2．两个固定点电荷A 和B 各带电－q 和－4q ，相距为d ，如何选择和放置第三个点电荷C 才能使 点电荷C 处于平衡状态？ 3．A 、B 、C 是三个完全相同的对地绝缘的金属球，已知原来仅有其中的一个球带电，现将A 球 先后与B 、C 接触，再把A 、C 放在相距为L 的两个位置上，测得A 、C 两球的库仑力为F ，若从三个球的初始状态起，改用C 球先后与B 、A 接触，再把A 、C 放在相距为L 的两个位置 上，测得A 、C 两球的库仑力为F 41，由此可判定原来带电的球是( ) A ．A B ．B C ．C D ．无法确定 4．“真空中两个点电荷相距10cm ，它们之间相互作用力大小为9×10－4N 。当它们合在一起时， 成为一个带电荷量为3×10－8C 的点电荷。问原来两电荷的带电荷量各是多少？”某同学求解如下： 根据电荷守恒定律得 q 1＋q 2＝3×10－8C ＝a ① 根据库仑定律：b F k r q q =????==--2492 2221C 10910 9)1010( 以1 2q b q =代入①式得 q 12－aq 1＋b ＝0 解得 C )104109103(2 1)4(211516821---?-?±?=-±=b a a q 根号中的数值小于0，经检查，运算无误。试指出求解过程中的问题并给出正确的解答。 5．真空中两个点电荷A 和B 电荷量相等，都等于2×10－5C 们相距8cm 。有另一正电荷C ，电荷 量为5×10－7C 。C 到A 和B 的距离相等，距AB 连线3cm 。求：(1)A 和B 都带正电；(2)A 带正电、B 带负电，两种情况下，C 所受的力。 6．如图所示，有三个点电荷A 、B 、C 位于一个等边三角形的三个顶点 上，已知A 、B 都带正电荷，A 所受B 、C 两个电荷的静电力的合力 如图中F A 所示。那么可以判定点电荷C 所带电荷的电性为( ) A ．一定是正电 B ．一定是负电 C ．可能是正电，也可能是负电 D ．无法判断

新概念第一册练习题全

新概念英语第一册练习题 Lesson1—Lesson2 一、填空 1.打扰啦 ____________________ 2.请再说一遍__________________ 3.谢谢你 ____________________ 4.不用谢______________________ 5.手表 ______________________ 6.房子________________________ 7.预订 ______________________ 8.铅笔________________________ 9.你的 ______________________ 10.非常地_____________________ 二、从下面A、B、C三个选项中选出正确的答案，并把正确的字母编号写在括号里。( ) 1. Mrs. White ___ a pair of red shoes. A. is B. have C. has ( ) 2. Do you like the grey shirt? No, I ___ . A. am B. do C. don’t. ( ) 3. The children ___ wearing yellow shoes. A. am B. is C. are ( ) 4. How much ___ the trousers? A. are B. is C. be ( ) 5. What’s ___ job? He’s a bus driver. A. her B. his C. he ( ) 6. I want to ___ a bank manager. A. is B. am C. be ( ) 7. What ___ he do? A. does B. do C. is ( ) 8. ___ T- shirt is this? It’s Jane’s. A. Who’s B. Who C. Whose ( ) 9.Let’s go and ask ___. A. her B. she C. he ( ) 10. My uncle is ___ ambulance driver. A. a B. an C. / ( ) 11. I have ___ brother or sister. A. not B. a C. no ( ) 12. The lady is ___ Canada. A. from B. at C. for ( ) 13. The child ___ an egg. A. is B. has C. have ( ) 14. Janet usually does ___ homework after dinner. A. my B. his C. her ( ) 15. Can you help ___ take a photo? A. me B. I C. we 三、阅读短文。

第1章课后习题参考答案

第一章半导体器件基础 1．试求图所示电路的输出电压Uo，忽略二极管的正向压降和正向电阻。 解： （a）图分析： 1）若D1导通，忽略D1的正向压降和正向电阻，得等效电路如图所示，则U O=1V，U D2=1-4=-3V。即D1导通，D2截止。 2）若D2导通，忽略D2的正向压降和正向电阻，得等效电路如图所示，则U O=4V，在这种情况下，D1两端电压为U D1=4-1=3V，远超过二极管的导通电压，D1将因电流过大而烧毁，所以正常情况下，不因出现这种情况。 综上分析，正确的答案是U O= 1V。 （b）图分析： 1.由于输出端开路，所以D1、D2均受反向电压而截止，等效电路如图所示，所以U O=U I=10V。

2．图所示电路中， E

解： （a）图 当u I＜E时，D截止，u O=E=5V； 当u I≥E时，D导通，u O=u I u O波形如图所示。 u I ωt 5V 10V uo ωt 5V 10V （b）图 当u I＜-E=-5V时,D1导通D2截止，uo=E=5V； 当-E＜u I＜E时，D1导通D2截止，uo=E=5V； 当u I≥E=5V时，uo=u I 所以输出电压u o的波形与（a）图波形相同。 5．在图所示电路中，试求下列几种情况下输出端F的电位UF及各元件(R、DA、DB)中通过的电流：( 1 )UA=UB=0V；( 2 )UA= +3V，UB = 0 V。( 3 ) UA= UB = +3V。二极管的正向压降可忽略不计。 解：（1）U A=U B=0V时，D A、D B都导通，在忽略二极管正向管压降的情况下，有：U F=0V mA k R U I F R 08 .3 9.3 12 12 = = - =

地理必修3第一章练习题及答案

地理必修3 第一章练习题1 2011.5 一、单选题 1.关于区域的叙述,正确的是： A.区域是在地球表面占有一定空间的地区,有明显的界限 B.区域是自然生成的,以自然的山脉和河流为界 C.区域可以有不同等级不同类型,区域内部的特征相对一致 D.区域是人为划分的,因而区域与区域之间差异不大 2、下列区域具有明确边界的是： ①行政区②自然带③热量带④干湿地区⑤三江平原⑥山东省青岛市A．①②③B．③④⑤C．①⑤⑥D．①⑥ 3、决定自然区域差异的基本因素是 ①地形②气候③水文④土壤⑤植被 A．①②B．②⑤C．③④D．④⑤ 4、东部季风区自然环境南北变化的特点体现了地理环境的 A．整体性B．经度地带性 C．垂直地带性D．纬度地带性 5、秦岭——淮河一线是我国一条重要的地理分界线，下列叙述正确的是 A.秦岭淮河作为自然分界线是明确的，无过渡性 B.所划分的区可进一步划分 C.线北的地区降水都在800mm以下 D.秦岭——淮河与行政区边界重合 6、下列不以秦岭――淮河一线为分界线的是 A．亚热带季风气候和温带季风气候 B．水田农业和旱地农业 C．农耕区和牧业区 D．湿润地区与半湿润地区 7、从东部季风区到西北干旱区再到青藏高寒区 ①区域面积依次减少，人口比重依次减小②地势逐级升高，降水逐渐减少③人类活动渐次加强，自然状态变化逐渐变大④土壤发育程度逐步降低，生物种类越来越少 A．①②B．②④C．①④D．①③ 8、造成西北干旱半干旱区内部差异的主要原因是 A．季风强弱不同造成的B．海陆位置不同造成的 C．气温随经度位置的变化造成的D．海拔高低悬殊造成的 9、西部干旱半干旱地区内部景观差异由东往西应该是 A．森林——森林草原——草原——荒漠草原——荒漠 B．荒漠——草原荒漠森林——草原——森林草原——森林 C．森林——草原——森林草原——荒漠——草原荒漠 D．荒漠——草原荒漠——草原——森林草原——森林 10、下列地理现象与其形成原因的组合，不正确的是 A．塔里木盆地沙漠广布——气候干旱，风力侵蚀、搬运和堆积作用明显 B．东部季风区土壤较肥沃——气候暖湿、多森林植被 C．青藏地区气候寒冷、冰川广布——海拔高度影响 D．西北地区气候干旱——纬度位置影响

新概念英语第一册练习题

新概念英语第一册1-12课习题New Concept English 专项训练 ? (1) 数词, 冠词, 介词, 动词时态变化, 比较级和最高级 一写出复数 1.???? radio?????????? 2. knife???????? 3. glass??????? 4. shelf? 5. boss???????? 6. dress??????? 7. housewife???????? ?? 9. leaf?????????? 10. church??????? 11. mouth???? 12. family 13. tie??????? 14. tomato???????? 15. piano?????? 16. baby 17. tooth???? 18. country??????? 19. key??????? 20 potato? 21. match??????? 22. box???? 23. hour???? 24. hero???? 25. Greman 二用冠词a, an, the 或 some , any 填空, 如果不需要,则用 / 代替. 1.???? Alice is ____ air-hostess. Her father is ____ engineer and her mother is _____ housewife. They all play ______ tennis very well. 2.???? He has ____ uncle and his uncle lives in ____ United Kindom. He first saw him in ____ autumn of 1978. 7. We need _____ ink, is there _____ left? 3.???? It is better to tell ______ truth than to tell _______ lies.

国际金融第一章练习题答案

国际金融（第四版）xxxx第一章答案 5.（1）1.6910（2）1.6910（3）1.6900 6. 1.6403 英镑/美元即1英镑美元[间接标价] 卖出美元价：1.690(卖出1.690美元可以买（得）回1英镑,即卖出时，1英镑兑1.690美元)，买进美元价：1.6910（1英镑可买进1.6910美元，即买进时，1英镑兑1.6910美元）（1）中国银行以什么价格向你买进美元？ 站在银行的角度，银行要买进美元，卖出英镑，则卖出英镑的价格越高越好，因此选1.6910（2）你以什么汇价从中国银行买入英镑？上课的时候有个男生举手说得对，其实这一题跟上一题的逻辑是一样的，只是提问的角度不一样。 站在银行的角度，银行卖出英镑，获得美元即买进美元，则卖出英镑价格越高获得美元越多，因此还是选1.6910 （3）如果你向中国银行卖出英镑，汇率多少？站在银行的角度相当于获得英镑即买入英镑，付出美元即卖出美元，也就是说花越少的美元得到英镑越好，因此选1.6900 6（1）7.8010（2）7.8000（3）7.8010 7. 1美元港元上课的时候我说应该始终站在银行角度，我认为是不对的，因为这样一来在外汇市场上中介就无利可图，这不符合逻辑，因此我们还是要看题目是在哪个立场。 在本题中，我们是在中介的立场，也就是说我们必须有利可图，按照这个立场才能作出正确的价格选择。（1）该银行向你买进美元，汇价是多少？ 在我的角度，银行向我买进美元，相当于我卖出美元，我要赚钱，当然要选贵的价格，所以是7.8010 （2）如果我要买进美元，按照什么汇率计算？

我买进美元，意味着越低的价格越好，因此汇率是7.8000 （3）如果你要买进港元，汇率多少？ 我买进港元，卖出美元，卖出美元的话当然是要卖贵价，所以选7.8010 8.（1）0.7685（2）0.7690 9.（1）1.2960（2）1.2940（3）1.2960 10.（1）1.4110（2）1.4100（3）1.4100 11.（1）7.8067（2）经纪人C ， 美元兑港币汇率，客户要以港币向你买进100万美元 （1）我是银行立场，客户买进美元，相当于我卖出美元，所以要卖贵一点，选7.8067（2）如果我想买回美元平仓，当然是想买最便宜的价格，所以我们首先排除了A、B两个经纪人。 由于我们是买回美元，站在经纪人的角度是卖出美元，他们要有利可图的话，给我们的价格自然是高的那个价格，即后面的那个价格。C、D经纪人一对比，就知道C更便宜，且价格为7.8060 13.以英镑买入日元的套汇价是1英镑=134.8336日元 解：（1）英镑和日元的标价方法不同，应当同边相乘，即1英镑＝103.40× ×1.3050日元＝日元公司需要卖出英镑，买进JPY 银行买入1英镑，支付公司134.8336日元★（公司卖出1英镑，收取银行134.8336日元★）银行卖出1英镑，收取公司135.3285日元 （2）银行买入1美元，支付公司103.40JPY②银行卖出1美元，收取公司103.70JPY银行买入1英镑，支付公司1.3040USD①银行卖出1英镑，收取公司1.3070USD公司需要卖出英镑，买进JPY。步骤：①公司卖出英镑，收取银行美元（银行买入英镑，支付公司美元）公司卖出1.0英镑，收取银行

第1章思考题及参考答案

第一章思考题及参考答案 １. 无多余约束几何不变体系简单组成规则间有何关系？ 答：最基本的三角形规则，其间关系可用下图说明： 图a 为三刚片三铰不共线情况。图b 为III 刚片改成链杆，两刚片一铰一杆不共线情况。图c 为I 、II 刚片间的铰改成两链杆（虚铰），两刚片三杆不全部平行、不交于一点的情况。图d 为三个实铰均改成两链杆（虚铰），变成三刚片每两刚片间用一虚铰相连、三虚铰不共线的情况。图e 为将I 、III 看成二元体，减二元体所成的情况。 2．实铰与虚铰有何差别？ 答：从瞬间转动效应来说，实铰和虚铰是一样的。但是实铰的转动中心是不变的，而虚铰转动中心为瞬间的链杆交点，产生转动后瞬时转动中心是要变化的，也即“铰”的位置实铰不变，虚铰要发生变化。 3．试举例说明瞬变体系不能作为结构的原因。接近瞬变的体系是否可作为结构？ 答：如图所示AC 、CB 与大地三刚片由A 、B 、C 三铰彼此相连，因为三铰共线，体系瞬变。设该 体系受图示荷载P F 作用，体系C 点发生微小位移 δ，AC 、CB 分别转过微小角度α和β。微小位移 后三铰不再共线变成几何不变体系，在变形后的位置体系能平衡外荷P F ，取隔离体如图所 示，则列投影平衡方程可得 210 cos cos 0x F T T βα=?=∑，21P 0 sin sin y F T T F βα=+=∑ 由于位移δ非常小，因此cos cos 1βα≈≈，sin , sin ββαα≈≈，将此代入上式可得 21T T T ≈=，()P P F T F T βαβα +==?∞+， 由此可见，瞬变体系受荷作用后将产生巨大的内力，没有材料可以经受巨大内力而不破坏，因而瞬变体系不能作为结构。由上分析可见，虽三铰不共线，但当体系接近瞬变时，一样将产生巨大内力，因此也不能作为结构使用。 4．平面体系几何组成特征与其静力特征间关系如何? 答：无多余约束几何不变体系?静定结构（仅用平衡条件就能分析受力） 有多余约束几何不变体系?超静定结构（仅用平衡条件不能全部解决受力分析） 瞬变体系?受小的外力作用，瞬时可导致某些杆无穷大的内力 常变体系?除特定外力作用外，不能平衡 5． 系计算自由度有何作用？ 答：当W >０时，可确定体系一定可变；当W <０且不可变时，可确定第４章超静定次数；W ＝０又不能用简单规则分析时，可用第２章零载法分析体系可变性。 6．作平面体系组成分析的基本思路、步骤如何？ 答：分析的基本思路是先设法化简，找刚片看能用什么规则分析。

(完整版)新概念第一册练习题(精心整理版)

新概念英语(一)习题集 Lesson1—Lesson2 一、填空 1.打扰啦_____________________ 2.请再说一遍__________________ 3.谢谢你_____________________ 4.不用谢______________________ 5.手表_______________________ 6.房子________________________ 7.预订_______________________ 8.铅笔________________________ 9.你的_______________________ 10.非常地_____________________ 二、从下面A、B、C三个选项中选出正确的答案，并把正确的字母编号写在括号里。( ) 1. Mrs. White ___ a pair of red shoes. A. is B. have C. has ( ) 2. Do you like the grey shirt? No, I ___ . A. am B. do C. don’t. ( ) 3. The children ___ wearing yellow shoes. A. am B. is C. are ( ) 4. How much ___ the trousers? A. are B. is C. be ( ) 5. What’s ___ job? He’s a bus driver. A. her B. his C. he ( ) 6. I want to ___ a bank manager. A. is B. am C. be ( ) 7. What ___ he do? A. does B. do C. is ( ) 8. ___ T- shirt is this? It’s Jane’s. A. Who’s B. Who C. Whose ( ) 9.Let’s go and ask ___. A. her B. she C. he ( ) 10. My uncle is ___ ambulance driver. A. a B. an C. / ( ) 11. I have ___ brother or sister. A. not B. a C. no ( ) 12. The lady is ___ Canada. A. from B. at C. for ( ) 13. The child ___ an egg. A. is B. has C. have ( ) 14. Janet usually does ___ homework after dinner. A. my B. his C. her ( ) 15. Can you help ___ take a photo? A. me B. I C. we 1

信号与系统课后习题答案—第1章

第1章 习题答案 1－1 题1－1图所示信号中，哪些是连续信号？哪些是离散信号？哪些是周期信号？哪些是非周期信号？哪些是有始信号？ 解： ① 连续信号：图（a ）、（c ）、（d ）； ② 离散信号：图（b ）； ③ 周期信号：图（d ）； ④ 非周期信号：图（a ）、（b ）、（c ）； ⑤有始信号：图（a ）、（b ）、（c ）。 1－2 已知某系统的输入f(t)与输出y(t)的关系为y(t)=|f(t)|，试判定该系统是否为线性时不变系统。 解： 设T 为此系统的运算子，由已知条件可知： y(t)=T[f(t)]=|f(t)|，以下分别判定此系统的线性和时不变性。 ① 线性 1）可加性 不失一般性，设f(t)=f 1(t)+f 2(t)，则 y 1(t)=T[f 1(t)]=|f 1(t)|，y 2(t)=T[f 2(t)]=|f 2(t)|，y(t)=T[f(t)]=T[f 1(t)+f 2(t)]=|f 1(t)+f 2(t)|，而 |f 1(t)|＋|f 2(t)|≠|f 1(t)+f 2(t)| 即在f 1(t)→y 1(t)、f 2(t)→y 2(t)前提下，不存在f 1(t)＋f 2(t)→y 1(t)＋y 2(t)，因此系统不具备可加性。 由此，即足以判定此系统为一非线性系统，而不需在判定系统是否具备齐次性特性。 2）齐次性 由已知条件，y(t)=T[f(t)]=|f(t)|，则T[af(t)]=|af(t)|≠a|f(t)|=ay(t) （其中a 为任一常数） 即在f(t)→y(t)前提下，不存在af(t)→ay(t),此系统不具备齐次性，由此亦可判定此系统为一非线性系统。 ② 时不变特性 由已知条件y(t)=T[f(t)]=|f(t)|，则y(t-t 0)=T[f(t-t 0)]=|f(t-t 0)|， 即由f(t)→y(t)，可推出f(t-t 0)→y(t-t 0)，因此，此系统具备时不变特性。 依据上述①、②两点，可判定此系统为一非线性时不变系统。 1－3 判定下列方程所表示系统的性质： )()()]([)()(3)(2)(2)()()2()()(3)(2)()()()()() (2''''''''0t f t y t y d t f t y t ty t y c t f t f t y t y t y b dx x f dt t df t y a t =+=++-+=+++=? 解：（a ）① 线性 1）可加性 由 ?+=t dx x f dt t df t y 0)()()(可得?????→+=→+=??t t t y t f dx x f dt t df t y t y t f dx x f dt t df t y 01122011111)()()()()()()()()()(即即 则 ???+++=+++=+t t t dx x f x f t f t f dt d dx x f dt t df dx x f dt t df t y t y 0212102201121)]()([)]()([)()()()()()( 即在)()()()()()()()(21212211t y t y t f t f t y t f t y t f ＋＋前提下，有、→→→，因此系统具备可加性。 2）齐次性 由)()(t y t f →即?+=t dx x f dt t df t y 0)()()(，设a 为任一常数，可得 )(])()([)()()]([)]([000t ay dx x f dt t df a dx x f a dt t df a dx x af t af dt d t t t =+=+=+??? 即)()(t ay t af →，因此，此系统亦具备齐次性。 由上述1）、2）两点，可判定此系统为一线性系统。

数学选修2-3第一章练习题含答案

选修2-3第一章练习试卷 一、选择题（共14小题；共70分） 1. 甲、乙两人计划从，，三个景点中各选择两个游玩，则两人所选景点不全相同的选法共有 A. 种 B. 种 C. 种 D. 种 2. 记者要为5名志愿者和他们帮助的2位老人拍照，要求排成一排，两位老人相邻但不排在两端，不同的排法共有( ) A. 1440种 B. 960种 C. 720种 D. 480种 3. 二项式展开式中的常数项为( ) A. -240 B. 160 C. -160 D. 240 4. 若，则的值是( ) A. -2 B. -3 C. 125 D. -131 5. 的二项展开式中，项的系数是( ) A. 45 B. 90 C. 135 D. 270 6. 现有名同学去听同时进行的个课外知识讲座，每名同学可自由选择其中的一个讲座，不同选 法的种数是 A. B. C. D. 7. 设的展开式中的系数为，二项式系数为，则 = ( ) A. 75 B. 60 C. 55 D. 45 8. 个人分件同样的服装，每人至多分件，而且服装必须分完，那么不同的分法种数是 A. B. C. D. 9. 某学校开设“蓝天工程博览课程”，组织个年级的学生外出参观包括甲博物馆在内的个博物 馆，每个年级任选一个博物馆参观，则有且只有两个年级选择甲博物馆的方案有( ) A. 种 B. 种 C. 种 D. 种 10. 某国际会议结束后，中、美、俄等国领导人合影留念，他们站成两排，前排人，后排人，中国领导人站在前排正中间位置，美、俄两国领导人也站前排并与中国领导人相邻，如果对其他国家领导人所站位置不做要求，那么不同的站法共有( ) A. 种 B. 种 C. 种 D. 种 11. 的展开式中，含的正整数次幂的项共有

第一章思考题20110925

《材料物理性能》思考题 第一章热学性能 1.1 概述 1、材料的热学性能包括、、和等。 2、什么是格波？ 3、若三维晶体由N个晶胞组成，每个晶胞中含有S个原子，则晶体中格波数为个，格波支数为个。 4、受热晶体的温度升高，实质是晶体中热激发出的声子的增加。 5、举例说明某一材料热学性能的具体应用。 1.2 热容 1、什么是比热容和摩尔热容（区分：定压摩尔热容和定容摩尔热容）？ 3、固体热容的经验定律和经典理论只适用于高温，对低温不适用！ 4、由德拜模型可知，温度很低时，固体的定容摩尔热容与温度的三次方成正比（德拜T3定律）。 5、金属热容由热容和热容两部分组成。 6、自由电子对热容的贡献在极高温和极低温度下不可忽视，在常温时与晶格振动热容相比微不足道！ 7、一级相变对热容的影响特征是什么？ 8、影响无机材料热容的因素有哪些？ 9、对于隔热材料，需使用低热容（如轻质多孔）隔热砖，便于炉体迅速升温，同时降低热量损耗。 10、什么是热分析法？DTA、DSA和TG分别是哪三种热分析方法的简称？举例说明热分析方法的应用。 1.3 热膨胀 1、什么是线或体膨胀系数？ 2、固体材料的热膨胀本质，归结为点阵结构中随温度升高而增大。 3、材料的热膨胀来自原子的非简谐振动。 4、材料热膨胀的物理本质可用曲线或曲线来解释。 5、熔点较高的金属具有较低的膨胀系数。 6、结构对称性较低的单晶体，其膨胀系数具有各向异性，不同的晶向有不同的线膨胀系数。一般来说，弹性模量高的方向将有较小的膨胀系数，反之亦然。（如石墨：平行于C轴方向的热膨胀系数大于垂直于C轴方向的热膨胀系数。） 7、举例说明一级相变对材料膨胀性能的影响。 8、钢的不同组织比容从大到小的顺序为：马氏体、渗碳体、铁素体、珠光体、奥氏体。 9、通常陶瓷制品表面釉层与坯体热膨胀系数的大小关系如何？为什么？

第一章 练习题

第一章练习题 一、单项选择题 1．管理者的管理目标是（）。 A．组织资源 B.提高效益 C. 正确决策 D.有效领导 2．管理者的首要职能是（）。 A．计划 B.领导 C. 控制 D.组织 3．高层管理者的主要工作是（）。 A．领导 B.协调 C. 决策 D.控制 4．与基层管理者和中层管理者相比，高层管理者更需要具备的技能是（）。 A．人际技能 B.领导技能 C. 技术技能 D.概念技能 5．管理者在作为组织的代表履行礼仪性和象征性义务时，其扮演的角色是（）。 A．人际关系方面 B.信息传递方面 C. 决策制定方面 D.组织管理方面 6．对基层管理人员而言，其管理技能侧重于（）。 A．谈判技能 B.技术技能 C. 人际关系技能 D.财务技能 7．有效的管理者在其管理活动中花费时间最多的是（）。 A．传统管理 B.人力资源管理 C. 网络管理 D.沟通 8．管理学家西蒙认为“管理就是决策”，其含义是（）。 A．决策的正确就意味着管理的成功 B．决策能力对于管理的成功起着很重要的作用 C．管理是在多个方案中选择一个正确的方案 D．管理是一个协调工作活动的过程 9．研究发现，一位管理者花费13%的时间在传统管理上，28%的时间在沟通上，11%的时间在人力资源管理上，48%的时间在网络联系上。根据这一研究结果，如下结论哪种是正确的（）。 A．一般管理者将主要精力集中在网络联系上 B．维护网络关系对管理者的成功贡献最大 C．从事人力资源管理活动对有效管理者相对贡献较小 D．成功管理者与有效管理者的管理风格相似 10．在公司制企业中，公司总经理与部门经理的考核有不同的标准，以下哪种标准更能体现二者的区别（）。 A．总经理比部门经理掌握公司经营方面的信息更全面 B．总经理比部门经理参加公司的会议更多

新概念一册全册复习测试卷

一写出下列单词的复数 1.radio 2. knife 3. glass 4. shelf 5. boss 6. dress 7. housewife 8.postman ______ _______ _________ ________ ______ _______ _________ _________ 9. leaf 10. church 11. mouth 12. family 13. tie 14. tomato 15. piano 16. baby ______ _______ _________ ________ ______ _______ _________ _________ 17. tooth 18. country 19. key 20 potato 21. match 22. box 23. hour 24. hero ______ _______ _________ ________ ______ _______ _________ _________ 二用冠词a, an, the 或some , any 填空, 如果不需要,则用/ 代替. 1. Alice is ____ air-hostess. Her father is ____ engineer and her mother is _____ housewife. They all play ______ tennis very well. 2. He has ____ uncle and his uncle lives in ____ United Kindom. He first saw him in ____ autumn of 1978. 7. We need _____ ink, is there _____ left? 3. It is better to tell ______ truth than to tell _______ lies. 4. Will you have ______ more tea? There’s plenty in the pot. 5. There is ___university near my home. Every Saturday evening,___ students hold ____ party. ___ are dancing, ____ are singing. They make a lot of noise. 6. Get me ________ cigarettes, please. ______ kind will do. 三用适当介词填空. 1. Can you see the words written _____ the blackboard? (in, on, by, with) 2. She is taking the children out _____ a walk. (in, on, for, by) 3. You can choose the best one ______ them. (in, on, among, by) 4. Jack broke the chocolate ______ several pieces. (in, on, with, into) 5. There are two bridges _____ the river. ( in, on, with, into) 6. There is a slogan(标语) ______ the wall. (on, in, over, above)

第一章思考题参考答案

参考答案 1．简述信息经济的主要标志。 答：信息经济是指以信息为经济活动之基础，以信息产业为国民经济之主导产业的一种社会经济形态。信息经济作为一种新型的社会经济结构，其主要标志有： （1）信息资源成为人类社会的主要经济资源；信息作为一种经济资源，其表现除了参与创造财富外，还表现在对质能资源的替代节约上，因此把信息当作资源来看待，不仅表现在对信息的重视上，还表现在对物质、能源的节约上。 （2）现代信息技术成为经济生活中的主要技术；信息技术是指开发和利用、采集、传输、控制、处理信息的技术手段。信息资源的开发，使信息量剧增，信息的经济功能骤显，如何把握瞬息万变的信息，为人们的经济生活服务，成为人类的一大难题。信息技术的适时出现，解决了人类的一大难题，信息技术的发展水平与应用程度，也就成为信息经济成熟与否的一个指标。 （3）产品中的信息成分大于质能成分；在信息经济社会，产品中的信息含量增加，信息成分大于质能成分。但并不是说每一种产品的信息成分均大于其质能成分，而是就整体而言的，除了增加物质产品中的信息含量外，信息产品日益丰富。也就是说，在信息经济社会中，产品结构以信息密集型物质产品和信息产品为主。 （4）产业部门中信息劳动者人数占总从业人数的比例大于物质劳动者所占比例；就信息劳动者人数而言，将其限制在产业部门，即农业、工业、服务业和信息产业部门的劳动者，不包括非产业部门的信息劳动者，其中信息劳动者人数占总从业人数的比例大于农业、工业、服务业中任何一个部门物质劳动者所占的比例。 （5）信息部门的产值占国民生产总值的比重大于物质部门产值所占的比重；信息部门的产值一般是指产业化了的信息部门的产值，信息部门产值占国民生产总值的比重大于农业、工业、服务业中任何一个部门产值所占比重。 2．简要叙述信息经济形成的时代背景。 答：（1）人类需求的渐进。随着社会的进步，生产力的发展，质能经济的产品已经不能完全满足人类的需要，只有靠增加物质产品中的信息含量，采用现代信息技术，发展信息产业，才有可能较好地满足人们的需要。这就促使质能经济向信息经济转化。 （2）物质经济的滞胀。二战后的经济危机使得资本主义发达国家不得不寻求对策，一方面实行大量资本输出，一方面按照“需求决定论”调整产业结构，使其向着知识、技术、信息密集型方向发展。 （3）质能资源的短缺。随着质能经济的发展，加之世界人口的急剧增长和资源的挥霍浪费，使质能资源频频告急，从1973年起，人类开始自觉主动地利用信息发展经济。