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已知m∈R,向量 a→ =(m,1), b→ =(2,﹣6),且 a→ ⊥ b→ ,则| a→ ﹣ b→ |=____.
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同类题1

阅读下列材料:

材料一:随着民族资本主义的产生和发展,出现了早期资产阶级维新思想家,他们所提出的维新主张有了明显的资产阶级特征。这体现在以下两个方面:首先,具有了比较明确的国家主权观念。反对外国侵略和维护民族独立,这是鸦片战争以来所有中国进步思想家的共同主张,但见识深浅大不相同。

----《中国全史》

材料二:光绪帝按照康有为提出的办法,发布了一系列变法令。主要内容有:发展农工商业;训练新式陆海军;创办报刊,开放言论;开办新式学堂培养人才。同时规定,今后科举考试废除八股文,取消多余的衙门和无用的官职。

材料三:(康有为)不但没有时时提醒光绪帝注意争取太后的支持,反倒时时鼓励光绪帝学习俄国彼得大帝“乾纲独断”,这就远离了当时的政治现实……康有为等维新派和光绪,从和平变法开始,却逐步走向武装政变之路,铤而走险,最后归于失败也就无可避免了……改革必然会损害一部分人的利益,这就要求改革者不能没有周全的设计。康有为、光绪对此几乎是全然不顾,因此很多改革措施都遭到强力反对,反对者并非都是上层的顽固分子,也有中下层官员、士子和民众。

----《回顾戊戌重温历史》

材料四:戊戌变政,首在裁官。京师闲散衙门被裁者不下十余处,连带关系,因之失职失业者将及万人,朝野震骇……

----《梦蕉亭杂记》

材料五:维新党在各个部门都实行大刀阔斧的改革工作,举世都为之震动。比起这个青年的中国来,就是日本的明治维新也瞠乎其后。

----《字林西报》

材料六:百日之间,维新之诏,联翩而下,变法神速,几有一日千里之势。

----黄鸿寿《清史记事本末》

材料七:变法失败的根本原因不在于变法的内容和策略上,而在于当时没有出现一个变法成功的整体的社会环境,以及与此相联系的强大的促进改革的政治和经济力量。

----李喜所《略谈戊戌变法的“保守”与“激进”》

材料八:“百日维新”虽然失败了,但它毕竟触动了传统的中国政治体制,为现代国家的建立作出了有益的尝试。以后发生的历次革命运动,从现代化的进程看,都与戊戌变法有着历史的连续性。也正因为如此,史学界才会把戊戌变法视作近代中国现代化进程的起点。

----《回顾戊戌重温历史》

材料九:戊戌变法在中国历史上第一次提出了由传统走向现代的系统方案,……倡导博爱、平等、自由、人权。这些思想观念并没有因戊戌变法的失败而消失其影响,相反,更加深入人心。……构成了中国现代化的逻辑起点。

----颜炳罡《戊戌变法与中国现代化进程》

同类题5

阅读理解

       A team of engineers at Harvard University has been inspired by Nature to create the first robotic fly. The mechanical fly has become a platform for a series of new high-tech systems. Designed to do what a fly does naturally, the tiny machine is the size of a fat housefly. Its mini wings allow it to stay in the air and perform controlled flight tasks.

    “It's extremely important for us to think about this as a whole system and not just the sum of a bunch of individual components (元件), ” said Robert Wood, the Harvard engineering professor who has been working on the robotic fly project for over a decade. A few years ago, his team got the go-ahead to start piecing together the components. “The added difficulty with a project like this is that actually none of those components are off the shelf and so we have to develop them all on our own,” he said.

       They engineered a series of systems to start and drive the robotic fly. “The seemingly simple system which just moves the wings has a number of interdependencies on the individual components, each of which individually has to perform well, but then has to be matched well to everything it' s connected to,” said Wood. The flight device was built into a set of power, computation, sensing and control systems. Wood says the success of the project proves that the flying robot with these tiny components can be built and manufactured.

        While this first robotic flyer is linked to a small, off-board power source, the goal is eventually to equip it with a built-in power source, so that it might someday perform data-gathering work at rescue sites, in farmers' fields or on the battlefield. “Basically it should be able to take off, land and fly around,” he said.

        Wood says the design offers a new way to study flight mechanics and control at insect-scale. Yet, the power, sensing and computation technologies on board could have much broader applications. “You can start thinking about using them to answer open scientific questions, you know, to study biology in ways that would be difficult with the animals, but using these robots instead,” he said. “So there are a lot of technologies and open interesting scientific questions that are really what drives us on a day-to-day basis.”