问题 单项选择题

有关对焊接材料的机械性能和化学成分的叙述中,说法不正确的是()。

A.在焊条的强度确定后,对于塑性、冲击性和抗裂性能要求较高、低温条件下工作的焊缝应选用碱性焊条

B.在对焊接结构受力复杂、刚性大、接头应力高、焊缝易产生裂纹的情况下,可以选用比母材强度高一级别的焊条

C.当焊件焊口处有较多的铁锈、油污和氧化皮、水分等脏物,且又无法清理时,应选用对铁锈、油污和氧化皮、水分敏感性小和抗气孔性较强的酸性焊条

D.低碳钢与低合金钢、不同强度等级的低合金钢等异种钢间的焊接,一般选用与较低强度等级钢材相匹配的焊条

答案

参考答案:B

多项选择题

To date, the bulk of the public debate about copyright and new technology has focused on an issue that I consider to be secondary, the issue of how new technology alters the balance of power between consumers and a relatively narrow group of producers, primarily the producers of certain types of music and film. By focusing so narrowly on that issue, and framing that issue as being about "kids’ stealing music," we run the risk of overlooking how bad copyright laws are increasingly affecting a much more important group of cultural producers.
I am the founder of Wikipedia, a charitable effort to organize thousands of volunteers to write a high-quality encyclopedia in every language of the world. We the Wikipedians have achieved remarkable success in our five-year history, and we’ve done it as volunteers freely sharing our knowledge. And yet, strangely enough, in addition to researching facts on hundreds of thousands of topics, we are forced to become copyright experts, because so much of our cultural heritage is being threatened by absurd limits on fair use of information in the public domain. I get two to three threatening lawyergrams each week; one I just received from a famous London museum begins, typically. "We notice you have a number of images on your website which are of portraits in the collection of [our museum] ... Unauthorized reproduction of such content may be an infringement ... "
I now respond with a two-part letter. First, I patiently and tediously explain that museums do not and cannot own the copyrights to paintings that have been in the public domain for hundreds of years. And then I simply say: "You should be ashamed of yourselves." Museums exist to educate the public about our shared cultural heritage. The abuse of copyright to corner that heritage is a moral crime.
The excuse normally given, that producing digital reproductions is costly and time-consuming, and museums need to be able to recoup that cost, is entirely bogus. Just give us permission, and Wikipedians will go to any museum in the world immediately to make high-quality digital images of any artwork. The solution to preserving our heritage and communicating it in a digital form is not to lock it up, but to get out of our way.
This issue, public-domain artworks, is about an abuse of existing law. But the law itself is also a problem. Copyrights have been repeatedly extended to absurd lengths for all kinds of works, whether the author aims to protect them or not. Even works that have no economic value are locked away under copyright, preventing Wikipedians from rewriting and updating them.
Every school system in the world faces the problem of expensive texts. Wikipedia shows a way to a solution, and we have founded a supporting project called Wikibooks to implement that solution. Here, thousands of volunteers are working to write textbooks. If we still lived in an era of reasonable copyright lengths (14 to 28 years, with registration), it would be no problem for us to seek out works of lapsed copyright, abandoned by their owners, and update them quickly. We could cut the costs of textbooks in schools radically, not just in the United States and other wealthy countries, but in the developing world as well.

What is the author’s attitude to the current copyright laws and what is his suggestion Give your comments.

And finally, the example set by Wikipedia and Wikibooks is beginning to spread, in an explosion of creativity. Another of my projects, the for-profit Wikicities, allows communities to form and build knowledge bases or other works on any topic of interest. Again, thousands of people are working to write the definitive guides to humor, films, books, etc., and they are doing this work voluntarily and placing it all under free licenses as a gift to the world. And, of course, here we have again all the same problems of abusive application of copyright law as at Wikipedia and Wikibooks. We obey the law; we are not about civil disobedience. We want only to be good, to do good and to share knowledge in a million different ways.We have the people to do it. We have the technology to do it. And we will do it, bad law or no. But good law, law that recognizes a new paradigm of collaborative creativity, will make our job a lot easier. Copyright reform is not about kids’ stealing music. It is about recognizing the astounding possibilities inherent in the honest and intelligent use of new technologies.

单项选择题 A型题