题干

如图所示,在空中以相同速度水平匀速直线飞行的加油机和受油机,在加油的过程中,下列说法正确的是(  )

A:加油机动能减小,重力势能减小,机械能减小

B:受油机动能减小,重力势能不变,机械能不变

C:加油机动能减小,重力势能不变,机械能减小

D:受油机动能减小,重力势能增大,机械能增大

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A

同类题1

阅读理解

    It is a popular Internet thing to focus on the upside of being in your 30s, and it is nice to know how to do basic modern-human-being things like paying your taxes and cooking a simple meal. But it can be a less-encouraging story at work: People in their late 20s to early 40s tend to report lower levels of job satisfaction and higher levels of emotional exhaustion than other age groups, according to new research.

    There's an obvious reason: These tend to be the ages when people have young children at home, and the researchers did find that this group reported feeling increasingly crunched for time. But adding to that pressure, coworker support also tends to decline at this age. Some researchers interpret the findings:

    Support from co-workers probably decreases in midlife as peers compete for limited resources(promotion bottlenecks are often encountered during this career stage. Also, whereas younger co-workers are often hungry to make up new social networks, and older workers seek identity-affirming work experiences in their remaining tenure(任期), mid lifers find it demanding enough just to maintain existing social networks. Meanwhile, time pressure likely increases as colleagues are all trying to enrich their own knowledge and experience.

    But the good news is that after about a decade of struggle, things start to pick back up again. Occupational psychologists say that happiness at work recovers when people reach their 40s, and that people in their 50s are more satisfied with their jobs than any other age group. Hang in there, 30-somethings-soon you will be older, but at least work will meet less frustration(挫折)!

同类题2

阅读下面的文字,完成下列各题。

刘文典:世上已无真狂徒

徐百柯

    2005年岁末,红学界颇不安宁,于是遥想当年,西南联大教授刘文典这样讲《红楼梦》:其时天已近晚,讲台上燃起烛光。不久,刘文典身着长衫,缓步走上讲台,坐定。一位女生站在桌边用热水瓶为他斟茶。先生从容饮尽一盏茶后,霍然站起,有板有眼地念出开场白“宁﹣吃﹣仙桃﹣一口,不﹣吃﹣烂杏﹣满筐!仙桃只要一口就行了啊……我讲《红楼梦》嘛,凡是别人说过的,我都不讲;凡是我讲的,别人都没有说过!今天给你们讲四个字就够了。”于是他拿起笔,转身在旁边架着的小黑板上写下“蓼汀花溆”四个大字。这次讲座原定在一间小教室开讲,后因听者甚众,改为大教室,还是容不下,只好改在联大教室区的广场上,学生席地而坐,洗耳恭听刘教授高论。

    刘氏在西南联大开《文选》课,不拘常规,常常乘兴随意,别开生面。上课前,先由校役提一壶茶,外带一根两尺来长的竹制旱烟袋,讲到得意处,就一边吸着旱烟,一边解说文章精义,下课铃响也不理会。有一次,他却只上了半小时的课,就忽然宣布说,今天提前下课,改在下星期三晚饭后七时半继续上课。原来,那天是阴历正月十五,他要在月光下讲《月赋》一篇。有学生追忆:届时,在校园里月光下摆下一圈座位,他老人家坐在中间,当着一轮皓月大讲其《月赋》,“俨如《世说新语》中的魏晋人物”。

    刘文典讲课时,同样是守旧派人物的吴宓也会前去听讲,而且总是坐在最后一排。刘教授闭目讲课,每讲到得意处,便抬头张目向后排望,然后问道“雨僧(是宓的字)兄以为如何?”每当这时,吴教授照例起立,恭恭敬敬地一面点头一面回答:“高见甚是,高见甚是。”两位名教授一问一答之状,惹得全场为之暗笑。

    一日,日机空袭,警报响起,联大的教授和学生四下散开躲避。刘文典跑到中途,忽然想起他“十二万分”佩服的陈寅恪身体羸弱且目力衰竭,于是便率几个学生折回来搀扶着陈往城外跑去。他强撑着不让学生扶他,大声叫嚷着:“保存国粹要紧!保存国粹要紧!”让学生们搀着陈先走。这时,只见他平素藐视的新文学作家沈从文也在人流中,便顾不得自己气喘如牛,转身呵斥道:“你跑什么跑?我刘某人是在替庄子跑,我要死了,就没人讲《庄子》了!你替谁跑?”

    刘文典多年潜心研究庄子,出版了十卷本《庄子补正》,陈寅恪为之作序,推崇备至。曾有人向刘氏问起古今治庄子者的得失,他大发感慨,口出狂言道:“在中国真正懂得《庄子》的,只有两个人。一个是庄周,还有一个就是刘某人。”狂则狂矣,当下不少见,但其背后那股子傲骨嶙峋的气度,却是今人学不来的。

    1928年,蒋介石掌握大权不久,想提高自己的声望,曾多次表示要到刘文典主持校务的安徽大学去视察,但刘拒绝其到校“训话”。后来,蒋虽如愿以偿,可是在他视察时,校园到处冷冷清清,并没有他所希望的那种隆重而热烈的欢迎场面。一切皆因为刘文典冷冷掷出的一句话:“大学不是衙门。”

    后来安徽发生学潮,蒋介石召见刘文典。之前刘氏曾有豪言“我刘叔雅(“叔雅”为刘文典的字)并非贩夫走卒,即是高官也不应对我呼之而来,挥手而去。蒋介石一介武夫耳,其奈我何!”见面时,刘称蒋为“先生”而不称“主席”,蒋很是不满。进而两人冲突升级,刘文典指着蒋介石说:“你就是军阀!”蒋介石则以“治学不严”为由,将刘当场羁押,说要枪毙。后来多亏蔡元培等人说情,关了一个月才获释。

    后人赞曰:“好个刘文典,名士风流,还是狷介狂人?我不知道,我能知道的是,今天,这样的知识分子已无处寻觅,所谓‘风流总被雨打风吹去’。”

(本文选自徐百柯《民国那些人》)

【相关链接】

    刘文典(1889﹣1958),安徽合肥人,字叔雅。现代杰出的文史大师,校勘学大师与研究庄子的专家。原籍安徽怀宁。历任北京大学教授、国立安徽大学校长、清华大学国文系主任。终生从事古籍校勘及古代文学研究和教学。著有《淮南鸿烈集解》、《庄子补正》、《三余札记》等。