题干

计算:

①x2﹣(x+2)(x﹣2)

②992﹣1

③(2a+b)4÷(2a+b)2

④(4a3b﹣6a2b2+2ab)÷2ab

⑤[(x+1)(x+2)﹣2]÷x.

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答案(点此获取答案解析)

解:①原式=x2﹣x2+4=4;②原式=(99+1)×(99﹣1)=100×98=9800;③原式=(2a+b)2=4a2+4ab+b2;④原式=2a2﹣3ab+1;⑤原式=(x2+3x)÷x=x+3.

同类题2

阅读下面的文字,完成文后各题。

    “让居民望得见山、看得见水、记得住乡愁”,这是以人为核心的新型城镇化建设的要求,也戳中了一些地方城镇化的软肋。一些乡村在变为城镇的过程中,虽然面貌焕然一新,但很多曾经让人留恋的东西却荡然无存。人们或多或少有这样的担忧:快速的、大规模的城镇化会不会使“乡愁”无处安放?要在城镇化进程中留住乡愁,不让“乡愁”变成“乡痛”,一个重要措施是要留住、呵护并活化乡村记忆。

    乡村记忆是乡愁的载体,主要包括两个方面:一方面是物质文化的记忆,如日常生活用品、公共活动场所、传统民居建筑等“记忆场所”;另一方面是非物质文化记忆,如村规民约、传统习俗、传统技艺以及具有地方特色的生产生活模式等。乡村物质文化记忆与非物质文化记忆常常相互融合渗透,构成一个有机整体。这些乡村记忆是人们认知家园空间、乡土历史与传统礼仪的主要载体。在城镇化的过程中留住他们,才能留住乡愁。这实质上是对人的情感的尊重。至于哪些乡村记忆真正值得保留,这一方面可以借助一些科学的评价体系进行合理的评估,另一方面可以广泛听取民意,然后进行综合甄选。在新型城镇化建设过程中,需要做好这方面的前期规划。

    仅仅留住乡村记忆而不进行呵护,乡村记忆会逐渐失去原有魅力。呵护乡村记忆,使其永葆“温度”,就要对相关记忆场所做好日常维护工作,为传统技艺传承人延续传统技艺创造条件,保持乡村传统活动的原有品质。比如,对一些乡土景观、农业遗产、传统生产设施与生产方法等有意识地进行整理维护。对于乡村中的集体记忆场所,如村落的祠堂、乡村的入口、议事亭、祭祀场所等,不可因为城镇化就让其全部消亡,而应对这些承载着人的情感和记忆的场所定期维修。既要让当地居民生产生活更为方便,又要让游子在故乡找到依恋感与归属感。

    如果说留住和呵护乡村记忆是一种消极型的留住乡愁的话,那么,活化乡村记忆则是一种积极型的留住乡愁。活化乡村记忆,就是在新型城镇化进程中深度挖掘乡村记忆与乡村传统产业,进行精细化、产业化升级,将“文”“人”“居”与“产”融合在一起,让原来的乡村记忆在新型城镇化进程中充满生机活力。这需要相应的公共设施与之配套,需要发展教育、医疗、商业、娱乐休闲产业等,使乡村记忆在新的时空条件下产生新的凝聚力。

(摘编自陆邵明《留住乡愁》

同类题4

      London has a new magazine. But it is not printed(印刷) on paper. Everyone who has a television can receive it because it is on TV.
In order to read this magazine you have to have a decoder (解码器). Each page of it is numbered, so you only have to dial the number to choose which subject you want to read about. There are all kinds of information ---everything is included from cooking to the latest sports news.
       If you want to read the news, the first thing you have to do is to turn to the back page, which has an easy-to-remember page number, 100 for example. Then you start choosing what you want to read. The news is on page 101 to 109, so you put in the numbers and the news appears written across your screen. Perhaps you want to go out in the afternoon, so you press 181, and a brightly colored weather map appears on the screen. But the weather is terrible, so you decide to go shopping and dial 162 for a list of the week’s best bargains. But should you drive or take the train? To answer that question you only have to press 189 for the traffic report. It is very simple to use. But probably the best thing about the service is that it is being updated all the time. Journalists type new material directly onto the screen and the whole pages of the magazine can be replaced in minutes.
         London already has three services. One, sent out by TV, is called ORACLE while the other two, on BBC, are called CEEFAX because they let you see facts. Although CEEFAX and ORACLE have been operating for some time, they have not been well publicized(宣传). BBC engineers do not think that their idea will ever replace books and newspapers because they can be taken with you everywhere. But many people would agree that is a breakthrough(突破) as great as the invention of printing, which could not just change our reading habits but our whole way of life.