A small group of Internet security specialists gathered in Singapore to start up a global system to make e-mail and e-commerce more secure, end the rapid growth of passwords and raise the bar significantly for Internet fraud, spies and troublemakers.
The Singapore event included an elaborate technical ceremony to create and then securely store numerical keys that will be kept in three hardened data centers there, in Zurich and in San Jose, Calif. The keys and data centers are working parts of a technology known as Secure DNS, or DNSSEC. DNS refers to the Domain Name System, which is a directory that connects names to numerical Internet addresses. Preliminary work on the security system had been going on for more than a year, but this was the first time the system went into operation, even though it is not quite complete.
The three centers are fortresses made up of five layers of physical, electronic and cryptographic security, making it virtually impossible to damage the system. Four layers are active now. The fifth, a physical barrier, is being built inside the data center.
The technology is viewed by many computer security specialists as a ray of hope amid the recent cascade of data thefts, attacks, disruptions and scandals, including break-ins at Citibank, Sony, Lockheed Martin, RSA Security and elsewhere. It allows users to communicate via the Internet with high confidence that the identity of the person or organization they are communicating with is not being tricked or forged.
Internet engineers like Dan Kaminsky, an independent network security researcher who is one of the engineers involved in the project, want to counteract three major deficiencies in today’s Internet. There is no mechanism for ensuring trust, the quality of software is uneven, and it is difficult to track down bad actors.
One reason for these flaws is that from the 1960s through the 1980s the engineers who designed the network’s underlying technology were concerned about reliable, rather than secure, communications. That is starting to change with the introduction of Secure DNS by governments and other organizations.
The event in Singapore capped a process that began more than a year ago and is expected to be complete after 300 so-called top-level domains have been digitally signed. Before the Singapore event, 70 countries had adopted the technology, and 14 more were added as part of the event. While large countries are generally doing the technical work to include their own domains in the system, the association of Internet security specialists is helping smaller countries and organizations with the process.
It is indicated in Paragraphs 1 and 2 that the global system the Internet security specialists gathered to start up______.

A:is still on the drawing board B:can put an end to Internet fraud C:has won specialists much acclaim D:has multi-advantages over previous ones

It is high time that such a practice （　）an end to.

A:is put B:be put C:was put D:must be put

Passage Four
Most cities and/or states in the U. S. collect a sales tax on almost everything you buy. You must ask when you move into a new community how much the local sales tax is, and what items are and are not taxable. Both taxable items and the amount of tax vary considerably from place, from one of two percent in some places up to eight or ten in others. The New York City sales tax, for examples, is currently 8% , so if you buy a pair of $40 shoes you will actually have to pay $43.20. This makes paying and getting correct change much more difficult ( not to mention making .everything more expensive). We say in America that only two things in life are unavoidable: one is death and the other taxes.
Another thing that makes money exchanges more complicated is tipping. The Chinese people have happily put an end to tipping, but Westerners are still plagued with this indignity. Waiters and waitresses, cab drivers, hotel bellboys, barbers and hairdressers and all sorts of other people must be tipped. Their employers give them low wages because it is expected that you, the customer, will make up the difference. If you don’ t, the service person can’ t earn a living. Tipping also varies from place to place, generally in the area of 15% of your bill (before taxes), but again you should ask local residents whom to tip and how much.
There is another kind of tipping as well. You are generally expected to give something ( either cash or a bottle of whisky) to the mailman and to your building "super" at Christmas time. You should discuss this also with neighbors and colleagues.

Usually, taxable items and the amount of tax（）

A:have no difference from place to place in the U. S. B:are over 15% in the U. S. C:have been put an end in the U. S. D:vary from place to place in the U. S.

It is high time that such a practice ______ an end to.

A:is put B:be put C:was put D:must be put

Passage Four Most cities and/or states in the U. S. collect a sales tax on almost everything you buy. You must ask when you move into a new community how much the local sales tax is, and what items are and are not taxable. Both taxable items and the amount of tax vary considerably from place, from one of two percent in some places up to eight or ten in others. The New York City sales tax, for examples, is currently 8% , so if you buy a pair of $40 shoes you will actually have to pay $43.20. This makes paying and getting correct change much more difficult ( not to mention making .everything more expensive). We say in America that only two things in life are unavoidable: one is death and the other taxes. Another thing that makes money exchanges more complicated is tipping. The Chinese people have happily put an end to tipping, but Westerners are still plagued with this indignity. Waiters and waitresses, cab drivers, hotel bellboys, barbers and hairdressers and all sorts of other people must be tipped. Their employers give them low wages because it is expected that you, the customer, will make up the difference. If you don’ t, the service person can’ t earn a living. Tipping also varies from place to place, generally in the area of 15% of your bill (before taxes), but again you should ask local residents whom to tip and how much. There is another kind of tipping as well. You are generally expected to give something ( either cash or a bottle of whisky) to the mailman and to your building "super" at Christmas time. You should discuss this also with neighbors and colleagues.

Usually, taxable items and the amount of tax（）

A:have no difference from place to place in the U. S. B:are over 15% in the U. S. C:have been put an end in the U. S. D:vary from place to place in the U. S.

As in the field of space travel, so in undersea exploration new technologies continue to appear. They share a number of similarities with each other — as well as some important differences.
Manned submersibles (潜水器), like spaceships, must maintain living conditions in an unnatural environment. But while a spaceship must simply be sealed against the vacuum of space, a submersible must be able to bear extreme pressure if it is not to break up in deep water.
In exploring space, unmanned vehicles were employed before astronauts. In undersea exploration, on the other hand, men paved the way, only recently have unmanned remote-operated vehicles (ROVs) been put to use.
One reason for this is that communicating with vehicles in orbit is much easier than talking to these underwater. A vacuum am ideal medium for radio communications, but underwater communications are limited to much slower sound waves. Thus, most undersea vehicles—particularly ROVs— operate at the end of long ropes.
For a similar reason, knowing where you are undersea is much more difficult than in space. A spaceship’s position can be located by following its radio signal, or by using telescopes and radar. For an undersea vehicle, however, a special network of sonar (声纳) must be laid out in advance on the ocean’ floor in the area of a dive to locate the vehicle’s position.
Though undersea exploration is more challenging than outer space in a number of respects, it has a distinct advantage: Going to the ocean depths doesn’t require the power necessary to escape Earth’s gravity. Thus, it remains far less expensive.

Ocean exploration is not so expensive as space travel mainly because （　）.

A:it is not affected Earth’s gravity B:most undersea vehicles operate at the end of long ropes C:ROVs have been put to use D:there is no need for submersibles to get away from Earth’ s gravity

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Ocean exploration is not so expensive as space travel mainly because ______.

A:it is not affected Earth’s gravity B:most undersea vehicles operate at the end of long ropes C:ROVs have been put to use D:there is no need for submersibles to get away from Earth’ s gravity