将生石膏经过123℃的密闭式加热脱水得到A.α-半水硫酸钙 B.β-半水硫酸钙 C.

题型:单项选择题

问题:

将生石膏经过123℃的密闭式加热脱水得到

A.α-半水硫酸钙

B.β-半水硫酸钙

C.α-半水硫酸钙和β-半水硫酸钙

D.二水硫酸钙

E.无水硫酸钙

考点:口腔医学技术士口腔技士基础知识初级口腔技士基础知识2
题型:单项选择题

In the early days of the internet, the idea that it represented an entirely new and separate realm, distinct from the real world, was seized upon by both advocates and critics of the new technology. Advocates liked the idea that the virtual world was a placeless datasphere, liberated from constraints and restrictions of the real world, and an opportunity for a fresh start. For instance, John Perry Barlow, an internet activist, issued the "Declaration of the Independence of Cyberspace" in February 1996. He thundered, "Governments of the industrial world, I come from cyberspace, the new home of mind. Cyberspace does not lie within your borders. We are creating a world that all may enter without privilege or prejudice accorded by race, economic power, military force, or station of birth."

Where Mr. Barlow and other cyber-Utopians found the separation between the real and virtual worlds exciting, however, critics regarded it as a cause for concern. They worried that people were spending too much time online, communicating with people they had never even met in person in chat rooms, virtual game worlds and, more recently, on social-networking sites such as MySpace and Facebook. A study carried out by the Stanford Institute for the Quantitative Study of Society in 2000, for example, found that heavy internet users spent less time talking to friends and family, and warned that the internet could be "the ultimate isolating technology".

Both groups were wrong, of course. The internet has not turned out to be a thing apart. Unpleasant aspects of the real world, such as taxes, censorship, crime and fraud are now features of the virtual world, too. Garners who make real money selling swords, gold and other items in virtual game worlds may now find that the tax man wants to know about it. Designers of virtual objects in Second Life, an online virtual world, are resorting to real-world lawsuits in order to protect their intellectual property.

At the same time, however, some of the most exciting uses of the internet rely on coupling it with the real world. Social networking allows people to stay in touch with their friends online, and plan social activities in the real world. The distinction between online and offline chatter ceases to matter. Or consider Google Earth, which puts satellite images of the whole world on your desktop and allows users to link online data with specific physical locations.

All these approaches treat the internet as an extension or an attachment to the physical world, not a separate space. Rather than seeing the real and virtual realms as distinct and conflicting, in short, it makes sense to see them as complementary and connected. The resulting fusion is not what the Utopians or the critics foresaw, but it suits the rest of us just fine.

It can be inferred from the passage that()

A. virtual world is free from the dark sides of the real world

B. there is no difference between chatting online and offline now

C. people’s activities online can also affect their real world activities

D. people who make real money in virtual games have to pay taxes

题型:单项选择题

Asherman综合征属于()

A.子宫性闭经

B.卵巢性闭经

C.垂体性闭经

D.下丘脑性闭经

E.外伤性闭经

题型:单项选择题

中国现有荒漠化土地267.4万平方千米,其中:风蚀荒漠化187.3万平方千米;土壤盐渍化17.3万平方千米;冻融荒漠化36.3万平方千米。荒漠化土地主要分布在下图所示的9个省区,占荒漠化土地总面积的

99%。结合下图回答1~4题。

1、有关我国荒漠化的现状,正确的是[ ]

A、荒漠化最严重的是风蚀荒漠化,占荒漠土地的99%

B、荒漠化土地主要分布在西北内陆省区

C、荒漠化土地主要分布的9个省(区)年降水量都在400mm以下

D、长江以南的省(市、区)没有荒漠化土地

2、冻融荒漠化土地主要分布在[ ]

A、甘肃、河北

B、新疆、内蒙古

C、陕西、宁夏

D、青海、西藏

3、荒漠化防治的核心是[ ]

A、恢复自然植被

B、恢复荒漠化土地的生产潜力

C、协调人与自然的关系

D、建立荒漠化预警系统

4、占全国荒漠化比例最高的省区,其荒漠化形成的主要原因是[ ]

A、自然植被人为破坏严重

B、土地疏松水土流失严重

C、深居内陆气候干旱

D、农牧业生产方式落后

题型:单项选择题

气管插管和气管切开的并发症有()

A.喉头水肿

B.牙齿松动

C.误入食管

D.切口出血

E.皮下或纵隔气肿

题型:单项选择题

FAS对火灾信息的处理优先级为:1级(最高)();2级(次高):FAS-BAS接口(车站火灾),OCC下发(隧道火灾)。

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