有A、B、C三种元素,A元素是一种金属元素,其单质X是生活中常见的金属,具有良好

题型:问答题

问题:

有A、B、C三种元素,A元素是一种金属元素,其单质X是生活中常见的金属,具有良好的抗腐蚀性能;B元素形成的一种单质Y露置于空气中容易自燃;C元素形成的单质Z是人类呼吸不可缺少的物质.按要求填空:

(1)A元素的名称______;

(2)单质Y的名称______;

(3)B、C两种元素形成的氧化物的化学式______;

(4)金属单质X抗腐蚀性能良好的原因______.

考点:物质的鉴别物质的推断
题型:问答题

成人尿比重正常参考值是

A.1.005~1.025

B.晨尿>1.025

C.1.015~1.025

D.1.015~1.020

E.1.105~1.025

题型:问答题

站在山脚下的人

27岁时,他从牧师转行去当画家,深信自己会在绘画艺术上有所成就。

  一天,他拿着自己的几幅临摹画作,去巴黎向一位知名的画家求教,希望他能指点一二。可一连去了好多次,对方都以他的作品太稚嫩,根本不具备绘画天赋为由拒绝给他指导,甚至连面都懒得见。

  无奈之下,他只好守在这位画家的院门口,希望能在他出门时拦住他。

  一天,画家果然被他等到了,“我对您的才华仰慕已久,请您务必花几分钟时间,指点一下我的作品。好吗?”说完,他便将自己的画双手奉上。

  可让他没想到的是,这位画家不但没有伸手去接画,反而以无比轻蔑的语气说道:“让我去看一个无名小卒的画,除了浪费我的时间外,没有任何意义。”

  对方的话极大地伤害了他的自尊,但他还是稳了稳情绪,然后微笑着说道:“如果把绘画艺术比作一座高山,那么现在的您无疑是站在山顶的那个人,而我则毫无疑问是站在山脚的那个,您若是朝下看我,自然觉得我渺小得如同一只蚂蚁。”

  大画家听后哈哈大笑:“既然你懂得这个道理,就应该知趣地离我远一点!”

  他点了点头:“从下一刻起,我便会离您远远的。可是,难道您就不想知道山脚下的人看山上的人是怎样的感觉吗?”

  “什么感觉?高山仰止?”大画家得意地反问。

  “不,我在山脚朝上看您,同样也觉得您渺小无比。”他淡淡地答道。

  就在那位画家惊愕不已时,他接着说道:“人是不能永远站在山顶的,无论他站得多高,始终都是要下来的;而站在山脚的人,只要肯努力,也一定有登上山顶的一天,不是吗?”

  后来的他,通过自己的努力,终于攀上了绘画艺术的最高峰。不错,他正是世界上最著名的画家之一——文森特·梵高。

小题1:本文叙述了一件什么事情?请用简洁的语言概括。(3分)

                                                                                

小题2:结合文章内容,分析梵高是一个怎样的人。(3分)

                                                                               

小题3:文中划线句“人是不能永远站在山顶的,无论他站得多高,始终都是要下来的;而站在山脚的人,只要肯努力,也一定有登上山顶的一天”,你赞同这个观点吗?为什么?(3分)

                                                                                

小题4:自选角度赏析这篇文章在塑造人物形象方面最成功的一种写作手法并说明理由。(3分)

                                                                                        

小题5:站在山顶和站在山脚的两个人,虽然地位不同,但在对方眼里,同样的渺小。从中你明白了什么道理?(3分)

                                                                         

题型:问答题

【问题4】
支持可变比特率(VBR)业务;支持面向连接的业务,其比特率是可变的。常见业务为压缩的分组语音通信和压缩的视频传输。请问根据其业务描述是属子图10-3中高层中的哪一级

题型:问答题

Astronaut Jim Voss has enjoyed many memorable moments in his career, including three space flights and one space walk. But he recalls with special fondness a decidedly earthbound experience in the summer of 1980, when he participated in the NASA-AS-EE Summer Faculty Fellowship Program. Voss, then a science teacher at West Point, was assigned to the Marshall Space Flight Center’s propulsion lab in Alabama to analyze why a hydraulic fuel pump seal on the space shuttle was working so well when previous seals had failed. It was a seemingly tiny problem among the vast complexities of running the space program. Yet it was important to NASA because any crack in the seals could have led to destructive results for the astronauts who relied on them.

"I worked a bit with NASA engineers," says Voss, "but I did it mostly by analysis. I used a handheld calculator, not a computer, to do a thermodynamic analysis. "At the end of the summer, he, like the other NASA-ASEE fellows working at Marshall, summarized his findings in a formal presentation and detailed paper. It was a valuable moment for Voss because the ASEE program gave him added understanding of NASA, deepened his desire to fly in space, and intensified his application for astronaut status.

It was not an easy process. Voss was actually passed over when he first applied for the astronaut program in 1978. Over the next nine years he reapplied repeatedly, and was finally accepted in 1987. Since then he has participated in three space missions. The 50-year-old Army officer, who lives in Houston, is now in training for a four-month mission as a crew member on the International Space Station starting in July 2000.

Voss says the ASEE program is wonderful for all involved. "It brings in people from the academic world and gives NASA a special property for a particular period of time. It brings some fresh eyes and fresh ideas to NASA, and establishes link with our colleges and universities," Voss explains. "There’s an exchange of information and an exchange of perspectives that is very important."

For the academic side, Voss says, the ASEE program also "brings institutions of higher learning more insight into new technology. We give them an opportunity to work on real-world problems and take it back to the classroom. \

How many flights will Voss have finished if his four-month mission starting in July 2000 ends up successfully ?()

A. Three

B. Two

C. Four

D. five

题型:问答题

下列关于鉴定可溶性还原糖、脂肪和蛋白质时所用的试剂及出现的颜色正确的是()。

A.斐林试剂(砖红色)、双缩脲试剂(紫色)、苏丹Ⅲ染液(红色)

B.斐林试剂(砖红色)、苏丹Ⅲ染液(紫色)、双缩脲试剂(红色)

C.苏丹Ⅲ染液(红色)、双缩脲试剂(紫色)、斐林试剂(砖红)

D.斐林试剂(砖红色)、苏丹Ⅲ染液(橘黄色)、双缩脲试剂(紫色)

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