A block chain is a data structure that stores...

A block chain is a data structure that stores time-ordered data in an ever-growing list, like an accounting ledger (分类账簿). The block chain data structure is maintained using a distributed, peer-to-peer network of computers with no central “master”. As with many new concepts, block chain technology generates much optimism and also a huge amount of interest and excitement. Just what is it good for?

In short, block chains may improve any process where people need to access, confirm, send or store information securely. This information could be a person’s identity, a product’s shipment history or digital property like money.

Typical databases, spreadsheets (电子数据表), and ledgers store information about objects, people, and the interactions between them. Much of the world’s information, from credit card transactions to medical and financial records, is stored in these types of systems.

These types of systems have considerable, well-documented weaknesses that arise from their being centralized. A centralized record is hard to understand and is exposed to unauthorized access or distribution. It is also, because it is a ‘master’ copy, exposed to permanent changing or deletion.

Block chains are also used to store information. Crucially, however, they differ in two ways.

First, information is parceled up into blocks and sealed. Bitcoin, for example, which is the most famous practical example of a production block chain, stores all transactions across the network every ten minutes or so in a single, newly formed block. Each block is then added to the previous one to form a chain.

Second, this “chain of blocks” is not stored centrally. Instead, each block is copied and distributed around an entire network of peers - be they individuals, public institutions, or businesses - using distributed ledger technology. (The terms “block chain” and “distributed ledger” are often used interchangeably; for the sake of clarity, block chain technologies tend to employ distributed ledger technology.)

Each time someone adds a new block to the chain, meanwhile it is added to everyone’s copy.

1.What is the biggest strength of a block chain?

A.It promotes people’s enthusiasm about new technology.

B.It strengthens the security of processing information.

C.It enables people to store more data in time order.

D.It stores a large part of world’s information.

2.The typical systems used to store information are weak in that ________.

A.they are difficult to operate B.they can be accessed easily

C.they have a central “master” D.they store considerable documents

3.The passage is developed mainly by ________.

A.making comparisons B.giving examples

C.making a list D.showing the effect and causes

4.What’s the author’s purpose in writing the passage?

A.To analyze the weaknesses of typical systems.

B.To encourage the popularity of the block chain.

C.To introduce the new concept of the block chain.

D.To compare the two different data structures.

高三英语阅读理解困难题查看答案及解析

Now that so much data is stored and circulated electronically, a library might seem to be a slightly outdated concept. However, a huge proportion of the world’s information and learning is still not available electronically, so libraries retain their importance for research and study. It is should also be remembered that libraries store books, inscriptions(铭文), and documents that are beautiful, and valuable not just for their contents, but also for their historic and artistic significance.

British Library (United Kingdom, London)

The British Library was created by Act of Parliament in 1972. Previously, the library had been part of the British Museum, where the famous circular reading room had accommodated researchers including Karl Marx, who worked on Das Kapital there, as well as Oscar Wilde and Mohandas Gandhi. The British Library is now housed in a new building in St. Pancras, London, where its treasures include two Gutenberg Bibles, the Lindisfarne Gospels, and one of Leonardo da Vinci’s notebooks.

Library of Congress(United States, Washington, D. C)

Founded in 1800 with the private collection of Thomas Jefferson, the Library of Congress is in fact the USA’s National Library, although only Congress members and employees can borrow books. It receives two copies of everything published in the United States. The Library of Congress was burned by the British Army in 1812, and severely damaged by fire again in 1851. The collection includes many rare books and drawings, and two Stradivarius violins.

National Library of China(Beijing)

Holding over 30 million books and documents, and visited by over five million people every year, this is the largest collection of Chinese writing in the world, and the largest library is Asia. It includes Chinese inscriptions on bone, stone, and tortoise shell which date back as far as the sixteenth century BC, and some of the oldest printed documents in existence as well as items in foreign languages and many rare books.

1.Despite the current electronic world, libraries are of importance because ________.

A. they are historically and artistically significant

B. they play an important role in preserving written accounts

C. they have available places for readers to rest

D. they are as convenient as electronic resources

2.Which of the following statements on British Library is TRUE?

A. The library has the most famous circular reading room in the world

B. Both Karl Marx and Oscar Wilde worked and lived in British Library

C. British Museum was once in charge of the British Library

D. All of Leonardo da Vinci’s notebooks are kept there

3.Library of Congress differs from other two libraries in the fact that ________.

A. not all people are allowed to borrow books

B. its collection includes many rare written works

C. it was created by the British Army in 1812

D. Thomas Jefferson has nothing to do with its foundation

4.In National Library of China, you are able to ___________.

A. find copies of everything published in the US

B. read Chinese inscriptions on various materials before the 16th century BC

C. borrow rare books and books written in different languages

D. have access to treasures like Gutenberg Bibles and Lindisfarne Gospels

高三英语阅读理解中等难度题查看答案及解析

It is        the customers’ needs that has made chain stores so popular in big cities in China.

高三英语单项填空简单题查看答案及解析

It is ___ the customers’ needs that has made chain stores so popular in big cities in China.

高三英语单项填空困难题查看答案及解析

It is ___________ the customers’ needs that has made chain stores so popular in big cities in China.

高三英语单项填空中等难度题查看答案及解析

Google is one of the world’s biggest data storage companies, 1. (store) people’s work, photos, emails and everything else. It has a popular Internet search engine(引擎), which scans the Web pages that are relevant 2. the words you have typed in the search box.

As we know, Google’s headquarters is big, and much of 3. (it) campus is green. There is so much grass 4. it would need a number of lawnmowers (割草机), but Google has a creative way about that. Instead of gas-powered 5. (machine), Google hires a great many goats 6. (clear) the lawns. They visit for about a week at 7. time, and about 200 of them come to work. The goats don’t use gas, pollute the air 8. make as much noise. And they have the advantage of being “a lot 9.　(attractive) to watch than lawnmowers”, as Google’s employees have put it.

And there are a load of dogs at Google, too. Google’s office is very dog-friendly. It says that letting people bring in their dogs 10. (make) everyone much happier.

高三英语短文填空中等难度题查看答案及解析

Walmart, which is one of the largest American supermarket chains, 　　 some of its stores open 24 hours on Mondays through Saturdays.

A.keeps B.keep　 C.have kept D.had kept

高三英语单项填空中等难度题查看答案及解析

Walmart, which is one of the largest American supermarket chains, 　　　　　 some of its store open 24 hours on Mondays through Saturdays.

A. keeps　　　　　　　　 B. keep　　　　　　　     C. have kept　　　　　　     D. had kept

高三英语单项填空中等难度题查看答案及解析

Walmart，which is one of the largest American supermarket chains，________ some of its stores open 24 hours on Mondays through Saturdays.(2012·安徽)

A．keeps　 B．keep　 C．have kept　 D．had kept

高三英语单项填空简单题查看答案及解析

Computer power is moving into the “cloud”—networks of data centres that use the Internet to supply all kinds of services, from e-mail and social networks to data storage and analysis.

The rise of cloud computing is rapid and causing huge changes in the tech industry. The old guard is suffering: this week’s $67 billion merger (合并) between Dell and EMC, makers of computers and storage devices respectively (分别), was a marriage forced by the rise of the cloud. Disruptive (捣乱的) newcomers are blooming: if Amazon’s cloud-computing unit were a stand-alone public company, it would probably be worth almost as much as Dell and EMC combined.

The gains for customers have been equally dramatic. Compared with older IT systems, cloud computing is often much cheaper. It adds tremendous flexibility: firms that need more computing capacity no longer have to spend weeks adding new servers and installing software. In the cloud they can get hold of it in minutes. Their applications can be updated continually, rather than just every few months. Individual users can reach their e-mails, files and photos from any device. And cloud services also tend to be more secure, since providers know better than their customers how to protect their computing systems against hackers.

But cloud computing makes one problem worse. In the old IT world, once a firm or a consumer had decided on an operating system or database, it was difficult and costly to switch to another. In the cloud this “lock-in” is even worse. Cloud providers go to great lengths to make it easy to upload data. They accumulate huge amounts of complex information, which cannot easily be moved to an alternative provider.

Cloud firms also create a world of interconnected services, software and devices, which is convenient but only for as long as you don’t venture (冒险) outside their universe. Being locked in to a provider is risky. Firms can start to tighten the screws by increasing prices. If a cloud provider goes bust (崩溃), its customers may have trouble getting back their data.

These risks have already caused a debate about whether the cloud needs stricter regulation. Some European politicians want to force cloud providers to ensure that data can be moved between them. That is too heavy-handed, because strict rules will inhibit (阻碍) innovation in what is still a young industry. The history of computing suggests that common standards may well appear naturally in response to customers’ demands—just as in personal computers, where it is now much easier to use the same files on different systems.

In the meantime, a few commonsense measures can reduce the risk of lock-in. Firms that use more than one cloud provider to host their data are less affected. So are those that keep their most important information in their own data centres. Consumers can take precautions, too. Some services are better than others at enabling users to move data between providers (Google does well on this score). Cloud computing promises its users many benefits, but don’t mistake it for some sort of digital heaven.

1.The author takes “the merger between Dell and EMC” for example to show ________.

A. the influence of cloud computing on computer and storage device makers

B. the miserable sufferings of old computer companies

C. the rapid development of new computer companies

D. the interaction between old companies and newcomers

2.With wide applications of cloud computing customers can ________.

A. pay less for the older IT systems

B. gain more computing capacity quickly

C. know better about defeating the hackers

D. install software within weeks

3.The problem of “lock-in” can be dangerous because ________.

A. it should ensure data can easily be moved to another provider

B. it can create a network of services connected with devices

C. it may make it difficult for customers to recover their data

D. it will discourage an argument about stricter rules

4.It can be inferred from the last two paragraphs that ________.

A. the European politicians’ advice is perfect

B. customers’ demands play a role in setting standards

C. lock-in is caused by firms’ storing information in their own centres

D. Google enables users to provide services and move data

5.Which of the following sayings can best express the main idea of the passage?

A. Everything has its time and that time must be watched.

B. The grass looks greener on the other side of the fence.

C. A candle lights others and consumes itself.

D. Every white has its black, and every sweet has its sour.

高三英语阅读理解简单题查看答案及解析