题干

在△ABC中,AB·BC=3,△ABC的面积S∈[
3
2
3
2
],则ABBC夹角的取值范围是(  )

A:π4,π3

B:π6,π4

C:π6,π3

D:π3,π2

上一题 下一题 0.0难度 选择题 更新时间:2012-08-27 06:15:05

答案(点此获取答案解析)

B

同类题4

阅读理解

    A research has shown that nearly 90 percent of traffic accidents are caused by human errors. So our aim is a fully autonomous car that gets rid of the cause of most accidents: the driver. Researcher Hodgson points out, “For safety, the faster you can remove humans, the better, even if there are unfortunately a few accidents from new causes. It s a question of balancing the number injured or killed by autonomous vehicles with the people whose lives are potentially saved.”

    It’s an idea that Elon Musk, chief executive of electric car company Tesla Motors, has long believed. His company are determined to be the first to deliver a fully autonomous vehicle to consumers. Last year, Musk announced that Tesla’s 2017 goal was “to do an example drive of full autonomy all the way from LA to New York…and have the car park itself.”

    However, even Tesla admits that there are problems to overcome—the software needs further validation and the appropriate regulatory approval needs to be in place. Indeed, recent crashes of Tesla vehicles and Google cars confirm that the software isn’t ready yet.

    The UK government appears committed to encouraging the development of autonomous vehicles. It’s supporting four city trials, publishing the Modem Transport Bill to reduce red tape around their introduction and adapting the legal system to take into account problems such as insurance liability when a human isn’t in control of a vehicle.

    The insurance industry is similarly eager to help increase autonomy in cars. As the Association of British Insurers (ABI) points out, “More than 90 per cent of road accidents are caused by human error.” This costs motor insurers a shocking £20m per day in claims.

同类题5

辛亥革命既是中国近代史的重大事件,也是史学研究关注的重点。阅读材料,回答问题。

材料一     清政府的政治改革使地方政治人物的参政热情日益高涨,同时经济新政极大地刺激了人们的物欲,促进了兴办实业的浪潮。但清政府在铸币、路权上的新政举措却使地方相关群体十分不满……辛亥革命要在全国取得成功,单靠孙中山深刻的革命思想和他领导的中国同盟会起义是远远不够的,它需要社会大背景的配合,而清末新政在教育与舆论等方面的改革为辛亥革命提供了有利的文化环境。

——郭世佑《论清末新政与辛亥革命的关系》

材料二     “起而革命者,代不乏人,然不过一朝一姓之变革而已。孙中山之革命则为国体之改革,与一朝一姓之变革迥然不同。”

——张謇《张季子·文录》

材料三     法学教授高全喜谈道:“清帝不是逊位给一家一姓的王朝,而是逊位给了一个未来的立宪共和政体,这是它与中国传统禅让的不同之处。”

——《立宪时刻》

材料四     “文革”结束后,辛亥革命史研究重新步入正轨,国内外的相关研究得出如下的一些认识。在政治史方面,辛亥革命促进了中国政治近代化的进程;在思想文化史方面,辛亥革命则是一场重大的思想启蒙运动;在经济史方面,辛亥革命有利于工业化的进程;在社会史方面,辛亥革命造成20世纪初中国社会各个层面的深刻剧变,推动了整个中国社会在20世纪的进步;革命史方面,辛亥革命是承前启后的革命分水岭;在民族史方面,辛亥革命极大地促进了民族意识的觉醒。在中国史方面,辛亥革命埋葬了封建帝制,推动了近代化进程,……在世界史方面,“辛亥革命在东方被压迫民族的解放运动中具有承前启后的重要地位”。

——摘编自《走出辛亥革命评价问题的困境》