题干

固体混合物A是由Mg、CuO、Na2SO4、Na2CO3、BaCl2、BaSO4中的几种混合而成为,为确定其成分,进行如图实验.(假设每步反应均恰好完全反应)

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同类题2

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辩证看压力

    ①人生在世,大都喜欢活得自由自在,恐怕极少有人愿意为他人所逼、受环境所迫。但是,外界压力是客观存在的,一般来说不受人的主观意愿支配,具有某种必然性。换个角度,用发展的、辩证的观点看,外界压力也有可能是人们获得发展与成就的机遇和先导,并不一定都是坏事。

    ②从历史上看,生存压力带给人类发展进步。在恶劣环境下,有巢氏“构木为巢以避群害”;在病痛之下,燧人氏“钻燧取火以化腥臊”;在饥饿之下,神农氏“制耒耜,教民农作”。可见,外在压力迫使人类学会了盖房子、煮食物、种粮食。人类社会能有今天这样发达的科学技术、生产方式,在很大程度上与人类克服外来压力的奋斗过程相关。

    ③对于做学问来说,压力之下能产生出重大成就。这样的例子,古今中外有很多。史载:“文王拘而演《周易》;仲尼厄而作《春秋》;屈原放逐,乃赋《离骚》;左丘失明,厥有《国语》。”曹植的七步诗,更是在以死相逼的巨大压力下产生的。曹植富于才学,受其父曹操赏识,然而却遭其兄曹丕忌恨。曹丕称帝后,一日召曹植,命他于七步之内成一诗,否则处死。曹植于悲愤之下,写成了著名的七步诗:“煮豆燃豆萁,豆在釜中泣。本是同根生,相煎何太急。”这首面对生死而成就的诗,不但保住了曹植的性命,也为中国文坛留下一篇千古佳作。

    ④毋庸讳言,如果没有外界的种种压力,许多人生活的基本轨迹就是循规蹈矩、安于现状,而不是改变现状、推陈出新。铁人王进喜当年说过:“井无压力不出油,人无压力轻飘飘。”有了压力,就有了革命、创造、发明与发愤的动力,就有了创作和改变的愿望与毅力。压力能够使人明确前进的方向。真正的强者,善于从顺境中找到阴影、从逆境中找到光亮,时时校准自己前进的目标。压力能够让人生发出超常的毅力。被动和逆境给人宝贵的磨炼机会,使人更能坚强不屈,表现出坚韧的美德。因此,压力能够激发出人们平常难以显现的智慧和创造力。

    ⑤不同的人面对压力会有不同的态度,当然结果也就大不相同。同样面对苦难和不幸,有的奋力抗争,成了强者、智者、英雄;有的则被压垮,成了乞丐、懦夫、失败者。如同巴尔扎克所说“不幸是天才的进身之阶、信徒的洗礼之水、能人的无价之宝、弱者的无底深渊”。面对压力,我们应以积极的态度去对待,抓住机遇,有效应对,使压力变动力,从而激发出创造美好生活的巨大潜力。

同类题4

阅读理解

    More and more people in America are celebrating the Indian holiday Diwali. Diwali is Hindi for “row of lights.” It is the most important holiday in India.

    Many people around the world are beginning to celebrate it as well. The United States is one of the places where the festival is becoming more common. Diwali celebrations can now be found at American landmarks like Disney land in California and New York City's Times Square. They are also held in many parks and museums.

    Neeta Bhasin created the Times Square event. She said Indian immigrants (移民) have found great success in America. But, she said, many Americans still do not know much about India. So, she decided to act. "I felt it's about time that we should take India to mainstream America and show India's rich culture, heritage, arts and variety to the world, "she said, "And I couldn't find a better place than the center of the universe: Times Square."

    Bhasin came to the United States from India 40 years ago. She is president of ASB Communications, the marketing firm behind Diwali at Times Square. Tens of thousands of people attend the event, now in its fourth year.

    In India, Diwali is a five-day harvest festival held just before the Hindu New Year. The exact dates change from year to year but Diwali is always in the fall. Celebrations include lighting oil lamps or candles called diyas. The lights represent "a victory of knowledge over ignorance, light over darkness, good over evil."

    A Diwali celebration will light up Disney California Adventure Park in Anaheim this year. Visitors can watch performances of traditional Indian dances and take part in a Bollywood dance party. The event is part of a Festival of Holidays program at the theme park to show cultural traditions from around the world.