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持证人员只能从事与其资格证级别、方法相对应的无损检验工作，其中()人员可编制一般的无损检测程序，并按检测工艺独立进行检测操作，评定检测结果，签发检测报告。
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用于传递空间互相垂直而不相交的两轴间的运动和动力。
It has always been difficult for the philosopher or scientists to fit time into his view of the universe. Prior to Einsteinian physics, there was no truly adequate formulation of the relationship of time to the other forces in the universe, even though some empirical equations included time qualities. However, even the Einsteinian formulation is not perhaps totally adequate to the job of fitting time into the proper relationship with the other dimensions, as they are called, of space. The primary problem arises in relation to things that might be going faster than the speed of light, or have other strange properties,
Examination of the Lorentz-Fitsgerald formulas yields the interesting speculation that if something did actually exceed the speed of light it would have its mass expressed as an imaginary number and would seem to be going backwards in time. The barrier to exceeding the speed of light is the apparent need to have an infinite quantity of mass moved at exactly the speed of light. If this situation could be leaped over in a large quantum jump--which seems highly unlikely for masses that are large in normal circumstances--then the other side may he achievable.
The idea of going backward in time is derived from the existence of a time vector that is negative, although just what this might mean to our senses in the unlikely circumstance of our experiencing this state cannot be conjectured.
There have been, in fact, some observations of particle chambers which have led some scientists to speculate that a particle called the tachyon may exist with the trans-light properties we have just discussed.
The difficulties of imagining and coping with these potential implications of our mathematical models points out the importance of studying alternative methods of notation for advanced physics. Professor Zuckerandl, in his book Sound and Symbol, hypothesized that it might be better to express the relationships bund in quantum mechanics through the use of a notation derived from musical notations. To oversimplify greatly, he argues that music has always given time a special relationship to other factors or parameters or dimensions. Therefore, it might be a more useful language in which to express the relationships in physics where time again has a special role to play, and cannot be treated as just another dimension.
The point of this, or any other alternative to the current methods of describing basic physical processes, is that time does not appear--either by common experience or sophisticated scientific understanding--to be the same sort of dimension or parameter as physical dimensions, as is deserving of completely special treatment, in a system of notation designed to accomplish that goal.
One approach would be to consider time to be a field effect governed by the application of energy to mass that is to say, by the interaction of different forms of energy, if you wish to keep in mind the equivalence of mass and energy. The movement of any normal sort of mass is bound to produce a field effect that we call positive time. An imaginary mass would produce a negative time field effect. This is not at variance with Einstein's theories, since the "faster" a given mass moves the more energy was applies to it and the greater would be the field effect The time effects predicted by Einstein and confirm by experience are, it seems, consonant with this concept. (565)
The passage supports the inference that ______.
The number of scientists and engineers going to America to study and work is dropping precipitously. An important reason is the length of time it now takes to get a visa. This is both deterring would-be visitors from coming, and hindering some of those who try. Not only may this lead to a decline in America's scientific strength, it is also an undeserved obstacle for many students.
Things are getting a little better--delays in visa processing, according to both America's State Department and academic observers, are shorter than a year ago. And only a small percentage of student-visa applications are held up for extremely long periods. Nonetheless, since the summer of 2003, applicants for student visas have been required to appear at an American consulate for an interview. Because consular staffs have not been expanded, this has led to delays of several weeks in order to sit for an interview that often lasts only a few minutes. Such a blanket requirement puts undue stress on both students and consulates, without yielding tangible security benefits. A more focused system makes more sense.
The current mess could prove costly to America. Its economic and military prowess owes a great deal to emigrating scientists and engineers. They were key members of the team which built its first atomic bomb in 1945, and they have played an important role ever since. In 2001, 35% of science and engineering doctorates a- warded by American universities went to foreign students, and foreigners comprise a similar proportion of America's scientific and engineering workforce.
Furthermore, several requirements have exacerbated delays, with little benefit to security. For example, checks on scientists working in areas that might relate to national security (exactly which areas are secret) are currently valid only for a year. Since such checks take on average two months to complete, and cannot be applied for within America, it thus becomes difficult to complete a course of study lasting five or six years. Visas should be granted for the duration of a course of study -if someone is not deemed a security risk today, it is un- likely he will be so a year from now. Legitimate visa holders should be allowed to enter and leave the country, and to apply for a renewal of their visas while still in America
There are also problems at home. The State Department and the Department of Homeland Security, which are jointly responsible for visas, are struggling to respond to the concerns of scientists but they are woefully ill- equipped files are exchanged twice weekly with the Federal Bureau of Investigation (FBI) on computer disks, while the FBI takes up to three days to reply that a person has not appeared on its database. Furthermore, the State Department keeps inadequate data about visa delays and applications. This is inexcusable. All manners of businesses use software today to segment and understand their customers' behavior. The government's failure to use the same technology is leading to both inefficiency and a decrease in security.
A more logical visa regime would make America safer, and those wishing to study or work there happier. Other countries are currently benefiting from the shortcomings in America's system. But change would, in the long term, serve even their interests. A return to honest global competition for scientists and engineers would be healthier and more productive.
The fact that key members of team that built America's first nuclear bomb were foreigners is used to ______.
听力原文： A fire broke out in a Buenos Aires nightclub, which packed with young revelers celebrating the New Year holidays. It killed at least 175 people when a crowd was trapped by locked doors, official said on Friday. At least 619 people were injured in the blaze, after a flare fired into the club's ceiling during a rock concert. The blaze may have claimed more victims because four of the club's six doors were inexplicably tied shut with wire.
Which is the most possible reason for such a disaster？
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