下列有关“筛分法”试验的叙述中,错误的有()。 A.本试验法适用于分析粒径大于0.0

题型:单项选择题

问题:

下列有关“筛分法”试验的叙述中,错误的有()。

A.本试验法适用于分析粒径大于0.074mm的土

B.标准筛分粗筛和细筛两种,粗筛和细筛以2mm筛孔直径为界

C.对于有粘聚性土样,可采用干筛法

D.对于含有部分粘土的砾类土,必须采用水筛法

考点:公路工程试验检测员水泥、水泥混凝土类水泥、水泥混凝土类题库
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依次填入下面一段文字横线处的语句,衔接最恰当的一组是(    )

如果把韩寒放到国际视野,他的优势可能多少会被剥除。________。________。________。一方面,这可能是最珍贵的,但另一方面,这也可能是最没有门槛的。________。________。由此推论,很多人是否从韩寒身上看到希望,这个就是见仁见智,不得而知。但有一点可以肯定,韩寒给年青一代传递的,绝不是希望的反义词。

①如果要学,思考是可以学的,勇气也是可以有的,至于智慧,也无非是后天修炼的。

②但是,和西方所熟知的钢琴家郎朗、篮球明星姚明相比,韩寒又是那么与众不同,你几乎能够一眼辨认他。

③但是韩寒不一样,他没有特殊的东西,他最大的资本,来自于他的智慧、他的独立、他的无所顾忌敢说敢干。

④这个时候,韩寒就显示出他强烈的草根特质,每个人都可以成为韩寒,都有可能成为韩寒,这是最了不得的——这种与共性注定韩寒是这个时代最特立独行但又最具平民特质的明星。

⑤郎朗和姚明走向世界,很明显靠的是特殊技艺,这份技术是一般人做不了、学不来的。

A.③②①⑤④

B.②⑤③①④

C.③②⑤①④

D.②③①⑤④

题型:单项选择题

美国东部时间2007年9月27日早7时20分,美国航空航天局(NASA)的“黎明”号探测器从佛罗里达州肯尼迪航天中心顺利升空,计划在未来8年时间里飞抵位于小行星带的终点站.“黎明”号探测器使用离子发动机,与传统的航天器化学燃料发动机不同,新型发动机将太阳能转化为电能,再通过电能电离惰性气体氙气的原子,产生时速达14.32万千米的离子流作为推动力,“黎明”号上安装了3个离子推进器和2个巨大的太阳能板,双翼间距近20米,足以为它提供穿越太空的能量,燃料利用效率是传统化学燃料发动机的10倍. 离子推进器是新一代航天动力装置,可用于卫星姿态控制和轨道修正.推进剂从图中P处注入,在A处电离出正离子,BC之间加有恒定电压,正离子进入B时的速度忽略不计,经加速后形成电流为I的离子束后喷出.已知推进器获得的推力为F,单位时间内喷出的离子质量为J,为研究问题方便,假定离子推进器在太空中飞行时不受其他外力,忽略推进器运动速度.

(1)求加在BC间的电压U;

(2)为使离子推进器正常运行,必须在出口D处向正离子束注入电子,试解释其原因.

题型:单项选择题

Civil-liberties advocates reeling from the recent revelations on surveillance had something else to worry about last week: the privacy of the billions of search queries made on sites like Google, AOL, Yahoo and Microsoft. As part of a long-running court case, the government has asked those companies to turn over information on its users’ search behavior. All but Google have handed over data, and now the Department of Justice has moved to compel the search giant to turn over the goods.
What makes this case different is that the intended use of the information is not related to national security, but the government’s continuing attempt to police Internet pornography. In 1998, Congress passed the Child Online Protection Act (COPA), but courts have blocked its implementation due to First Amendment concerns. In its appeal, the DOJ wants to prove how easy it is to inadvertently stumble upon porn. In order to conduct a controlled experiment—to be performed by a UC Berkeley professor of statistics—the DOJ wants to use a large sample of actual search terms from the different search engines. It would then use those terms to do its own searches, employing the different kinds of filters each search engine offers, in an attempt to quantify how often "material that is harmful to minors" might appear. Google contends that since it is not a party to the case, the government has not right to demand its proprietary information to perform its test. "We intend to resist their motion vigorously," said Google attorney Nicole Wong.
DOJ spokesperson Charles Miller says that the government is requesting only the actual search terms, and not anything that would link the queries to those who made them. (The DOJ is also demanding a list of a million Web sites that Google indexes to determine the degree to which objectionable sites are searched.) Originally, the government asked for a treasure trove of all searches made in June and July 2005 ; the request has been scaled back to one week’s worth of search queries.
One oddity about the DOJ’s strategy is that the experiment could conceivably sink its own case. If the built-in filters that each search engine provides are effective in blocking porn sites, the government will have wound up proving what the opposition has said all along—you don’t need to suppress speech to protect minors on the Net. "We think that our filtering technology does a good job protecting minors from inadvertently seeing adult content," says Ramez Naam, group program manager of MSN Search.
Though the government intends to use these data specifically for its COPA-related test, it’s possible that the information could lead to further investigations and, perhaps, subpoenas to find out who was doing the searching. What if certain search terms indicated that people were contemplating terrorist actions or other criminal activities Says the DOJ’s Miller, "I’m assuming that if something raised alarms, we would hand it over to the proper [authorities]." Privacy advocates fear that if the government request is upheld, it will open the door to further government examination of search behavior. One solution would be for Google to stop storing the information, but the company hopes to eventually use the personal information of consenting customers to improve search performance. "Search is a window into people’s personalities," says Kurt Opsahl, an Electronic Frontier Foundation attorney. "They should be able to take advantage of the Internet without worrying about Big Brother looking over their shoulders. \

The phrase "scaled back to" in the sentence "the request has been scaled back to one week’s worth of search queries" (para. 3) can be replaced by ______.

A.maximized to

B.minimized to

C.returned to

D.reduced to

题型:单项选择题

下列说法不正确的是(  )

A.两种元素组成的分子中一定只有极性键

B.共价化合物中一定存在极性共价键

C.非金属元素组成的化合物一定是共价化合物

D.稀有气体中不含化学键

题型:单项选择题

踢皮球:互相推诿()

A.燕归巢:时过境迁

B.破天荒:闻所未闻

C.睁眼瞎:目不识丁

D.纸老虎:不堪一击

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