IT4

精心整理

页脚内容 标准公差表

根据国际标准，以下为基本尺寸0-500mm,4-18级精度标准公差表。

公差值

基本尺寸 IT4 IT5 IT6 IT7 IT8 IT9 IT10 IT11 IT12 IT13 IT14 IT15 IT16 IT1大于 到 μm

mm

- 3 3 4 6 10 14 25 40 60 0.1 0.14 0.25 0.4 0.6 1

3 6 4 5 8 12 18 30 48 75 0.12 0.18 0.3 0.48 0.75 1.2

6 10 4 6 9 15 22 36 58 90 0.15 0.22 0.36 0.58 0.9 1.5

10 18 5 8 11 18 27 43 70 110 0.18 0.27 0.43 0.7 1.1 1.8

18 30 6 9 13 21 33 52 84 130 0.21 0.33 0.52 0.84 1.3 2.1

30 50 7 11 16 25 39 62 100 160 0.25 0.39 0.62 1 1.6 2.5

50 80 8 13 19 30 46 74 120 190 0.3 0.46 0.74 1.2 1.9 3

80 120 10 15 22 35 54 87 140 220 0.35 0.54 0.87 1.4 2.2 3.5

120 180 12 18 25 40 63 100 160 250 0.4 0.63 1 1.6 2.5 4

180 250 14 20 29 46 72 115 185 290 0.46 0.72 1.15 1.85 2.9 4.6

250 315 16 23 32 52 81 130 210 320 0.52 0.81 1.3 2.1 3.2 5.2

315 400 18 25 36 57 89 140 230 360 0.57 0.89 1.4 2.3 3.6 5.7

Different countries have different cultures，which cause some misunderstanding. Here is just one example of it. In many countries，people will tell you what they think you want to hear，whether or not it is 1 . To them，this is the 2 thing to do Americans，though，it is considered confusing，even 3 ，to avoid telling the true facts. Even when avoiding the truth is done only to be polite，it 4 no difference. In America，this would still be considered the wrong thing to do. It is helpful to 5 that different cultures consider some matters more important than others. For Americans， 6 and truth are most important. One of the 7 things that can be said about someone in America is that“you cannot trust him. ” 8 such differences in values among the many cultures of the world，we come to know a certain truth. We realize it is natural misunderstandings will 9 . “How far is it to the next town?”an American traveler asks a man standing by the 10 of a road. In some countries，a man may realize the traveler is tired and 11 to reach the next village. 12 ，he will politely say，“Just down the road. ”He thinks this is more 13 ，gentler，and therefore the answer the traveler wants to hear. So the American drives alone for many more hours 14 he comes to the village. The traveler is angry，feeling 15 . He thinks that the man has purposely 16 to him. The man must have known quite well what the 1 7 was，the American traveler thinks. If a visitor to the United States asked an American standing at the edge of a road how far the next town was, the American would think it dishonest if he said it was near 18 he knew it was actually 24 miles away. 19 he，too，would be sympathetic with the tired traveler，he would say，“You have a long way to go yet；it at least 24 miles more. ”The traveler might be disappointed，but he would know what to 20 In this case，there would be no misunderstanding. 1. A. realistic B. exact C. proper D. true 2. A. gracious B. moral C. polite D. refined 3. A. discouraged B. dishonest C. distressed D. disturbed 4. A. encourages B. exists C. tells D. makes 5. A. remember B. remind C. recall D. mind 6. A. certainty B. trust C. reputation D. justice 7. A. worst B. best C. common D. criminal 8. A. Thinking B. Believing C. Considering D. Reflecting 9. A. exist B. increase C. spread D. occur 10. A. limits B. margin C. boundary D. edge 11. A. enthusiastic B. eager C. nervous D. impatient 12. A. Therefore B. However C. Anyway D. Still 13. A. assuring B. comforting C. encouraging D. promising 14. A. while B. until C. before D. after 15. A. treated B. tricked C. joked D. trapped 16. A. misled B. deceived C. fooled D. lied 17. A. space B. distance C. length D. range 18. A. where B. when C. what D. which 19. A. While B. When C. However D. Even 20. A. assume B. suppose C. imagine D. expect 1. D 2. C 3. B 4. D 5. A 6. B 7. A 8. C 9. D 10. D 11. B 12.A 13. C 14. C 15. B 16. D 17. B 18. B 19. A 20. D Passage l In the future, marketing one drug to all people with the same symptoms may seem as silly as opening a shoe store that sells one size of shoes. But one-size-fits-all medications are precisely what the big drug companies are selling today. And why not? A single big seller, such as Prilosec or Lipitor. can earn a pharmaceutical(药学的)firm billions of dollars. Well, that familiar world is about to change. Breakthrough research on the human genome(基因组)--which promises to explain genetic differences among people so that drugs can be fine tuned to work better with fewer side effects--may mean the slow demise(终止)of the drug industry blockbuster(兴隆). The reason?“Blockbusters don’t work for everybody, ”says Jorge Leon. Genomics director at Quest Diagnostics. Scientists have long known that many drugs don’t work for 30 percent to 60 percent of the people for whom they are prescribed--or may even harm them. Now, research is revealing the reasons why that’s so. For example. new genetic tests could show that a third of patients taking a top hypertension(高血压)or cholesterol(胆固醇)一lowering drug would be better off on another product. Anxiety.“That’s a frightening concept to a pharmaceutical company. ”says Michael. “Personalizing treatments could cut into the sales of drugs that fuel today, s profits. ”Over time, some experts believe, the revelation that one drug doesn’t cure all will almost certainly force industry wide change, revamping(改进)everything from clinical trials to sales efforts. Giant drug companies financially are struggling to decide whether to be against that change or embrace it. On the one hand, companies are putting money in the hot new field of pharmacogenomics to figure out which drugs do and don’t work on specific individuals. But they are mostly mining that research to develop new drugs, not to figure out who should really be taking the drugs already on the market. “The scientists want to learn who can best benefit from existing drugs, while the sales and marketing people want to protect the cash cows. ”says Leon. 1. The author thinks that in the future . A. all drug companies will be producing the same drugs for all people B. people with the same symptoms might be taking different drugs C. people might have similar symptoms because of the drugs they use D. drug companies might be producing products other than drugs 2. The drug companies dislike the new way of drug production and sales because . A. they might lose money B. they might lose customers C. they might lose recognition D. they might break the law 3. Which of the following is TRUE according to the passage? A. Drug companies care more about patients than profits. B. Scientists want the patients to benefit from existing drugs. C. Drug companies pay scientists a lot to develop new drugs. , D. New drugs give patients new hopes for getting better. 4. Why does the author mention the shoe store in the first paragraph? A. Because shoes will be sold with drugs in the future. B. Because drugs will have as large a market as shoes in the future. C. Because shoes are as foolishly sold as drugs are today. D. To illustrate the poor marketing of drugs today. 5. Which of the following is probably the best title for the passage? A. What’s Best for Patients Isn’t Always Best for Profits. B. Patients Are Dying from Taking Different Drugs. C. New Business Styles in Drug Companies. D. Drug Companies with New Drug Sales Styles. l. B 2.A 3.B 4.D 5.A Unit 3 Passage l Fifteen-year-old freshman Charles“Andy”Williams, who is being held in the shooting in California that left two students dead and 13 wounded, was reportedly the butt of jokes, a weekend drinker and one who hung out at a local skate park with kids who did drugs. Had he and his peers received meaningful instruction in“character formation”. there’s a good chance their sense of respect for themselves and others would have held back the ridiculing and created a better atmosphere. Many youngsters have a difficult time seeing any moral dimension to their actions. Consequently, schools stress academic achievement but don’t always identify and reinforce the habits that students need to become virtuous. But there’s hope. More and more schools, from the rich suburbs to the inner cities, are realizing that good test scores aren’t enough if students aren’t taught to be responsible members of

IT4IT5IT6IT7IT8IT9IT10大于到-334610142540364581218304861046915223658101858111827437018306913213352843050711162539621005080813193046741208012010152235548714012018012182540631001601802501420294672115185250315162332528113021031540018253657891402304005002027406397155250

轮廓最大高度不平度平均高度轮廓的平均算术偏差取样长度光洁度

RyRzRal符号0.050.050.0130.10.10.0250.20.20.050.40.40.10.80.80.20.251.61.60.43.23.20.86.36.31.612.512.53.2-18-186.32525-35-35505012.5-70-7025100100-140140200200-280-280-50400400-100-560-560-ssss

0.8sss根据国际标准，以下为基本尺寸0-500mm, 4-18级精度标准公差表。

注：基本尺寸小于1mm时，无IT14至IT18。基本尺寸公

µm

--2.5ss

-sIT11IT12IT13IT14IT15IT16IT17IT18

600.10.140.250.40.611.4750.120.180.30.480.751.21.8900.150.220.360.580.91.52.21100.180.270.430.71.11.82.71300.210.330.520.841.32.13.31600.250.390.6211.62.53.91900.30.460.741.21.934.62200.350.540.871.42.23.55.42500.40.6311.62.546.32900.460.721.151.852.94.67.23200.520.811.32.13.25.28.13600.570.891.42.33.65.78.94000.630.971.552.546.39.7公差值

1 it的用法

it可用作代词、先行词及引导词等。

一, it 作代词:

1. 人称代词it，是第三人称单数中性，代表前文已提到过的一件事物

That vase is valuable. It’s more than 200 years old. 那个花瓶很珍贵，它有200多年的历史

I love swimming. It keeps me fit. 我喜欢游泳，它能使我保持健康。

2. it 可用来指婴儿。

It’s a lovely baby. Is it a boy or a girl? 宝宝真可爱，是男孩还是女孩？

3. it用以代替指示代词this, that.

-- What’s this? --- It’s a pen. —这是什么？ —是一支钢笔。

--- Whose book is that? --- It’s Mike’s. —那是谁的书？ —是迈克的。

4. it可指说话者心目中所指的人

Go and see who it is. 去看看是谁

--- Who is making such a noise? —是谁发出这样的吵闹声？

--- It must be the children. —一定是孩子们。 2 5. 虚词it无指代性，常用作没有具体意义的主语，表示天气、气候、温度、时间、地点、距离等意义的句子中。如：

It is half past three now. 现在是三点半钟。

It is six miles to the nearest hospital from here. 这里离最近的医院也有六英里。

It was very cold; it snowed and grew dark. 天气很冷；天下着雪，渐渐地变黑了