题干

定义函数y=fx,xD,若存在常数c,对任意x1D,存在唯一x2D的,使得
f
x
1
+
f
x
2
2
=c
,则称函数f(x)在D上的均值为c,已知fx=lgx,x[10,100],则函数fx=lgxx[10,100]上的均值为(   )

A:32

B:34

C:710

D:10

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答案(点此获取答案解析)

A

同类题2

阅读理解

    A Chinese consortium(联盟)led by China Railway Corp will participate in bidding for a high-speed railroad linking Singapore and Malaysia in 2018, marking another step in China's ambitious strategy to export its high-speed railway technologies to Southeast Asia.

    The consortium, consisting of eight companies including CRRC, China Railway Construction Corporation Ltd, China Railway Signal and Communication Co and Export-Import Bank of China, covers the design, construction, telecommunication, financing, operating and maintenance(维护)sectors for the high-speed rail network.

    A joint tender(招标)for the Kuala Lumpur-Singapore high-speed rail project was issued by the Malaysian and Singaporean government-owned utilities(公用事业)—MyHSR Corp and SG HSR,on Dec 20.According to a joint statement released by the two companies, the potential bidder would be responsible for the design, construction, financing, operating and maintenance of rolling stock and railway systems for the double-track line with a designed speed of 350 kilometers per hour.

    The tender is open to all companies, regardless of their location. A tender briefing will be held in Kuala Lumpur on Jan 23, and proposals need to be submitted by June 29. Submissions will be evaluated based on technical merit(优点), commercial robustness, financial sustainability and price. The preferred bidder will be selected by the end of next year. The governments of both countries signed a bilateral(双边的)agreement late in 2016 to begin the project. According to the agreement, the high-speed rail link is expected to become operational by Dec 31, 2026, and will cut travel time between Kuala Lumpur and Singapore to just 90 minutes.

    “The move indicates that China's State-owned enterprises have stopped cruel competition to hurt each other,” said Du Chunbu, a professor of rail transportation at Beijing Jiaotong University. “Instead, they have started to form a consortium to better compete with companies from Japan, South Korea, Germany and Canada by bringing their specialties into play.”

同类题3

阅读下面的文章,完成小题。

和父亲坐一条板凳

孙道荣

    上大学后的第一个暑假,回家。坐在墙根下晒太阳的父亲,将身子往一边挪了挪,对我说,坐下吧。印象里,那是我第一次和父亲坐在一条板凳上,也是父亲第一次喊我坐到他的身边,与他坐同一条板凳。

    第一次坐在父亲身边,其实挺别扭。不过,从那以后,只要我们父子一起坐下来,父亲就会让我坐在他身边。如果是我先坐在板凳上,他就会主动坐到我身边,而我也会像父亲那样,往一边挪一挪。

    工作之后,我学会了抽烟。有一次回家,与父亲坐在板凳上,闲聊,父亲掏出烟,自己点了一根。忽然想起了什么,犹豫了一下,把烟盒递到我面前说,你也抽一根吧。那是父亲第一次递烟给我。父子俩坐在同一条板凳上,闷头抽烟。烟雾从板凳的两端漂浮起来,有时候会在空中纠合在一起。而坐在板凳上的两个男人,却很少说话。与大多数农村长大的男孩子一样,我和父亲的沟通很少,我们都缺少这个能力。在我长大成人之后,我和父亲最多的交流,就是坐在同一条板凳上,默默无语。坐在同一条板凳上,与其说是一种沟通,不如说更像是一种仪式。

    父亲并非沉默讷言的人。年轻时,他当过兵,回乡之后当了很多年的村干部,算是村里见多识广的人了。村民有矛盾了,都会请父亲调解,主持公道。双方各自坐一条板凳,父亲则坐在他们对面,听他们诉说,再给他们评理。调和得差不多了,父亲就指指自己的左右,对双方说,你们都坐过来嘛。如果三个男人都坐在一条板凳上了,疙瘩也就解开了,母亲就会适时走过来喊他们,吃饭,喝酒。

    结婚之后,有一次回乡过年,与妻子闹了矛盾。妻子气鼓鼓地坐在一条板凳上,我也闷闷不乐地坐在另一条板凳上,父亲坐在对面,母亲惴惴不安地站在父亲身后。父亲严厉地把我训骂了一通。训完了,父亲恶狠狠地对我说,坐过来!又轻声对妻子说,你也坐过来吧。我坐在了父亲左边,妻子扭扭捏捏地坐在了父亲右边。父亲从不和女人坐一条板凳的,哪怕是我的母亲和姐妹。那是惟一一次,我和妻子同时与父亲坐在同一条板凳上。

    在城里终于有了自己的房子后,我请父母进城住几天。客厅小,只放了一对小沙发。下班回家,我一屁股坐在沙发上,指着另一只沙发对父亲说,您坐吧。父亲走到沙发边,犹疑了一下,又走到我身边,坐了下来,转身对母亲说,你也过来坐一坐嘛。沙发太小,两个人坐在一起,很挤,也很别扭,我干脆坐在了沙发帮上。父亲扭头看看我,忽然站了起来,这玩意太软了,坐着不舒服。只住了一晚,父亲就执意和母亲一起回乡去了,说田里还有很多农活。后来有了大房子,也买了三人坐的长沙发,可是,父亲却再也没有机会来了。

    父亲健在的那些年,每次回乡,我都会主动坐到他身边,和他坐在同一条板凳上。父亲依旧很少说话,只是侧身听我讲。他对我的工作特别感兴趣,无论我当初在政府机关工作,还是后来调到报社上班,他都听得津津有味。有一次,是我升职之后不久,我回家报喜,和父亲坐在板凳上,年轻气盛的我,一脸踌躇满志。父亲显然也很高兴,一边抽着烟,一边听我淘淘不绝。正当我讲到兴致时,父亲突然站了起来,板凳一下子失去了平衡,翘了起来,我一个趔趄,差一点和板凳一起摔倒。父亲一把扶住我,你要坐稳喽。不知道是刚才的惊吓,还是父亲的话,让我猛然清醒。这些年,虽然换过很多单位,也做过一些部门的小领导,但我一直恪守本分,得益于父亲给我上的那无声一课。

    父亲已经不在了,我再也没机会和父亲坐在一条板凳上了。每次回家,坐在板凳上,我都会往边上挪一挪,留出一个空位,我觉得,父亲还坐在我身边。我们父子俩,还像以往一样,不怎么说话,只是安静地坐着,坐在陈旧而弥香的板凳上,任时光穿梭。

(说明以上内容选自《思维与智慧》2015年第8期上,有增删)