题干


等比数列{an}的公比q>1,且第17项的平方等于该数列的第24项的值,则使成立的最小自然数n是(   )

A:10

B:11

C:19

D:20

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答案(点此获取答案解析)

D

同类题2

阅读下面的文章,完成后面题目。

爱因斯坦

苗  千

爱因斯坦(A1bert Einstein,1879—1955)这位出生于德国的犹太裔理论物理学家,因为对理论物理学的开创性贡献,早已成为“天才”的代名词和科学界的标志性人物。全世界研究爱因斯坦的专家和书籍多如牛毛,我们不可能通过一篇短文来总结爱因斯坦的天才或他的理论,如果只从科学史的角度去考量这位物理学家,就会发现他在德国甚至是整个欧洲物理学发展过程中的符号意义。

1879年3月14日出生于德国乌尔姆的爱因斯坦,在早期并不像很多传说故事中描述的那样,是一个智力发育迟缓且有语言障碍的小男孩,他很早就表现出了超强的领悟能力以及对自然界的好奇心。据他自己讲述,他第一次对自然界感到好奇,来自他爸爸送给他的一个小罗盘,那个始终坚定指向一个方向的罗盘指针使他第一次认识到了自然界的神奇。

15岁时爱因斯坦追随做生意失败的父母到意大利求学,后又转学瑞士,在学风开放的阿劳中学补习一年后考取了苏黎世理工学院,接受数学和物理学教育。随后,这位天才留在了充满着让他喜爱的自由气息的瑞士,却因找不到教职而成了专利局的一名小职员。当学术成就开始被全世界认可后,他开始执教于苏黎世大学,随后离开瑞士,执教于布拉格,后来又回到当时的世界物理学研究中心——德国柏林。

回顾爱因斯坦早年的求学和执教经历,与罗曼•罗兰笔下的人物——音乐家约翰•克里斯多夫倒有颇多相似之处,他们都是在少年时期对德国的沉闷空气感到压抑,之后游历欧洲,吸收各国文化的精髓,但最终在他们的作品中仍旧体现了德国思想和文化的条理性和深刻性。

爱因斯坦在少年时代完全无法忍受德国的应试教育,他因此选择在瑞士接受高中和大学教育。在工作轻松的伯尔尼专利局做小职员的同时,丝毫没有放弃对“同时性”进行不懈的、深刻的思考,最终发展成为狭义相对论,改变了人们对时间的认识。正是在瑞士放松自由的氛围中,他和几位好友成立了“奥林匹亚学院”,一起研读哲学和物理学的经典著作,以马赫、庞加莱和休谟等人的思想为后盾,对牛顿经典物理学发起挑战。

爱因斯坦在得到物理学界的认可之后,回到了德国。一方面可能是因为他认识到德国在彼时仍然是世界物理学研究的中心,柏林聚集了世界上最出色的物理学家;另一方面,成熟的爱因斯坦可能对于表面显得僵化、教条的德国式思维也有了更深刻的理解和认同。他的广义相对论,固然有着天才的迸发,但也有对于自然规律深刻的认识和艰苦卓绝的追求,这正是德国精神的体现。这位终生追求物理学和谐统一的物理学家喜欢莫扎特远胜于贝多芬,他认为贝多芬是在创造音乐,而莫扎特只是从天堂中把音乐“拿来”。他做出这个评论的时候,不会知道后人评价他开创广义相对论同样经历了像贝多芬一样孤独而悲壮的奋斗。

第二次世界大战中,爱因斯坦受到德国纳粹政府的胁迫出走美国,他的再次出走成为德国作为世界物理学研究中心开始凋零和美国科学界崛起的标志。这位一生热爱和平的物理学家作为美国公民度过了他平静的下半生,他的经历,不仅是传奇,俨然成为20世纪人类科学发展的一个缩影。

同类题5

根据短文理解,选择正确答案。

    People who have lost the ability to understand or use words due to brain damage are called aphasics(失语症患者).Such patients can be extremely good at something else.From the changing expressions on speakers' faces and the tones of their voices,they can tell lies from truths.

    Doctors studying the human brain have given a number of examples of this amazing power of aphasics.Some have even compared this power to that of a dog with an ability to find out the drugs hidden in the baggage.

    Recently,scientists carried out tests to see if all that was said about aphasics was true.They studied a mixed group of people.Some were normal;others were aphasics.It was proved that the aphasics were far ahead of the normal people in recognizing false speeches—in most cases,the normal people were fooled by words,but the aphasics were not.

    Some years ago,Dr.Oliver Sacks wrote in his book about his experiences with aphasics.He mentioned a particular case in a hospital.Some aphasics were watching the president giving a speech on TV.Since the president had been an actor earlier,making a good speech was no problem for him.He was trying to put his feelings into every word of his speech.

    But his way of speaking had the opposite effect on the patients.They didn't seem to believe him.Instead,they burst into laughter.The aphasics knew that the president did not mean a word of what he was saying.He was lying!

    Many doctors see aphasics as people who are not completely normal because they lack the ability to understand words.However,according to Dr.Sacks,they are more gifted than normal people.Normal people may get carried away by words.Aphasics seem to understand human expressions better,though they cannot understand words.