题干

设 f(x)={(x−a)2,x≤0x+
1
x
+a,x>0
  ,若 f(0) 是 f(x) 的最小值,则 a 的取值范围为(   )

A:-1,2

B:-1,0

C:1,2

D:0,2

上一题 下一题 0.0难度 选择题 更新时间:2018-10-18 05:31:26

答案(点此获取答案解析)

D

同类题2

阅读下文,回答问题。

集中营的课堂

程刚

      ①纳粹德国攻占波兰,控制着华沙。沙宁是刚来的老师,正给孩子们上课,几个纳粹兵来到学校,大声地对她说:“沙宁,跟我们走一趟吧,你还要藏到什么时候?”说完,他们便涌上来,将沙宁摁到了车上。

      ②孩子们都吓哭了,只有谢达快速跑回家,告诉爸爸赛夫,沙宁老师被抓走了。赛夫听到这个消息,不禁一惊,焦急地在屋里来回走着……

      ③第二天早上,谢达悄悄地来到集中营门口,他不知从哪里找到了一枚手雷,然后大叫着冲向纳粹看守,他很快被制服,投进了集中营。谢达很坚强,始终咬定手雷是捡来的,纳粹只好把他关起来。看守每天鞭打他,让他干着与年龄不相称的活,可他似乎能承受一切,他只想知道,沙宁老师是否还在这里,是否还活着。

      ④这天早上,谢达被惊醒,几个纳粹将一个全身血肉模糊的女人扔了进来,谢达一看,这不是沙宁老师吗?他突然一阵狂喜,和几位妇女一起把沙宁老师扶到板子上,沙宁伤得太重,一直在昏迷。纳粹没有从沙宁口中得到任何有价值的消息,还不想让她死,便给她医治。沙宁醒后,第一眼便看见了谢达。她有些激动,想问谢达怎么进来的。可她极度虚弱说不出话,聪明的谢达急忙小声地对沙宁说:“沙宁老师,我来上课。”沙宁一怔……

      ⑤沙宁成了集中营里的老师。纳粹严密监视着她的动向,希望能从沙宁的讲课中找到破绽。另外,这十几个孩子让他们伤透了脑筋。沙宁上课的时候,孩子们却很安静。为了让他们安静些,纳粹还假装慈悲地给孩子们买了画笔。沙宁对谢达非常好,除了给他上课,有时还教他画画……

      ⑥这一天 ,几名想逃跑的战俘又被他们抓回来折磨而死,然后再被吊起来,暴露在阳光下……一直以来,纳粹就是这样没有人性,凡是想逃跑的人,都会被处死并吊在营门外。每每看到这种场景,谢达心中充满了仇恨。

      ⑦这一天早上,天还没亮,谢达偷偷地走出房间,悄悄爬向纳粹士兵的油库,可就在他准备点燃火柴时,被纳粹哨兵发现,一颗罪恶的子弹穿透了他的胸膛,谢达当即倒下,然后被拖出门外吊起来示众。第二天中午,赛夫打通了关节,把谢达抱回家。他要给谢达穿上新衣服再埋葬,为此,他几度昏厥。

      ⑧四天后,盟军报纸大幅报道了赛夫送出情报,纳粹在波兰的毒气弹据点纷纷被摧毁的消息。如果再晚几天,这些毒气弹就会被运往前线,将会有成千上万盟军士兵中毒而亡。半个月后,沙宁被解救出来,她和赛夫都成了大英雄,一个催人泪下的故事也被披露出来。

      ⑨原来,沙宁掌握毒气弹据点的情报后,来到华沙想与赛夫接头,因泄密她被捕了。焦急的赛夫本想自己进集中营和沙宁接头,可他是地下组织的负责人,不能离开。便想出了让谢达攻击哨兵而进入集中营与沙宁接头的办法。沙宁的情报图一直记在脑海里,她便偷偷地教谢达画画,不久,谢达便能把地图完整地画出来。该怎样把情报送出呢?就在这时,谢达见到逃跑的人都会被处死吊在营门外,于是,他便想到了这个慷慨赴死的办法,悄悄地把地图画在了衣服里面……他知道,爸爸肯定会想办法把他抱回家,肯定会给他换套新衣服再埋葬,肯定会发现画在衣服里面的地图……

      ⑩谢达消逝在天堂里,但他用稚嫩的肩膀扛出的惊天壮举却深深地感染了我们,那个集中营的课堂里,上的是这世界上最感人的一课。

                                                                                                                                        (选自《情感读本·道德篇》,有删改)

同类题4

阅读短文,下列问题

C

Rob

     I don't think there is a solution to the environmental problems. The world population is now too large. We are going to run out of natural resources.

    Global warming shows us the effect that human beings have on the planet. Soon, millions of people will start leaving some parts of the world, because it will be impossible for them to live there any more, which in turn will create a whole new set of problems.

Louise

   The environmental situation is very serious, but I believe human beings can solve the problems.

   For example, we have already had clean ways of making electricity, like nuclear (原子能的) power and wind power.

   Besides, I think in the end, most people will want to help solve the problems. People just need to be made more aware of the problems and shown ways how they can help.

Michael

   We can now see that there has been a huge price to pay for the economic (经济的) development, because we have used a lot of natural resources and polluted the Earth.

   Of course, we can do many things to protect the Earth. For example, we can recycle (回收利用) or drive cars that pollute a bit less, or even use fewer plastic bags. However, I really don't know if these small things are going to be enough to solve the problems.

Rob

     I don't think there is a solution to the environmental problems. The world population is now too large. We are going to run out of natural resources.

    Global warming shows us the effect that human beings have on the planet. Soon, millions of people will start leaving some parts of the world, because it will be impossible for them to live there any more, which in turn will create a whole new set of problems.