题干

某地区有8所高中和22所初中.要了解该地区中学生的视力情况,下列抽样方式获得的数据最能反映该地区中学生视力情况的是(  )

A:从该地区随机选取一所中学里的学生

B:从该地区30所中学里随机选取800名学生

C:从该地区一所高中和一所初中各选取一个年级的学生

D:从该地区的22所初中里随机选取400名学生

上一题 下一题 0.0难度 选择题 更新时间:2018-10-14 08:07:39

答案(点此获取答案解析)

B

同类题2

阅读下列文字,完成下列小题

谏逐客书

李斯

    臣闻吏议逐客,窃以为过矣。

    昔穆公求士,西取由余于戎,东得百里奚于宛,迎蹇叔于宋,求丕豹、公孙支于晋。此五人者,不产于秦,而穆公用之,并国二十,遂霸西戎。孝公用商鞅之法,移风易俗,民以殷盛,国以富强,百姓乐用,诸侯亲服,获楚、魏之师,举地千里,至今治强。惠王用张仪之计,拔三川之地,西并巴蜀,北收上郡,南取汉中,包九夷,制鄢郢,东据成皋之险,割膏腴之壤,遂散六国之众,使之西面事秦,功施到今。昭王得范雎,废穰侯,逐华阳,强公室,杜私门,蚕食诸侯,使秦成帝业。此四君者,皆以客之功。由此观之,客何负于秦哉!向使四君却客而不内,疏士而不用,是使国无富利之实,而秦无强大之名也。

    今陛下致昆山之玉,有随、和之宝,垂明月之珠,服太阿之剑,乘纤离之马,建翠凤之旗,树灵鼍之鼓。此数宝者,秦不生一焉,而陛下说之,何也?必秦国之所生然后可,则是夜光之璧,不饰朝廷;犀象之器,不为玩好;郑、卫之女,不充后宫;而骏良駃騠,不实外厩;江南金锡不为用,西蜀丹青不为采。所以饰后宫、充下陈、娱心意、说耳目者,必出于秦然后可,则是宛珠之簪、傅玑之珥、阿缟之衣、锦绣之饰,不进于前;而随俗雅化、佳冶窈窕赵女,不立于侧也。夫击瓮叩缶、弹筝搏髀,而歌呼呜呜,快耳目者,真秦之声也。郑卫桑间、《昭虞》《武象》者,异国之乐也。今弃击瓮而就郑卫,退弹筝而取昭虞,若是者何也?快意当前,适观而已矣。今取人则不然。不问可否,不论曲直,非秦者去,为客者逐。然则是所重者,在乎色乐珠玉;而所轻者,在乎人民也。此非所以跨海内、制诸侯之术也。

    臣闻地广者粟多,国大者人众,兵强则士勇。是以泰山不让土壤,故能成其大;河海不择细流,故能就其深;王者不却众庶,故能明其德。是以地无四方,民无异国,四时充美,鬼神降福,此五帝三王之所以无敌也。今乃弃黔首以资敌国,却宾客以业诸侯,使天下之士,退而不敢西问,裹足不入秦,此所谓藉寇兵而赍盗粮者也。

    夫物不产于秦,可宝者多;士不产于秦,而愿忠者众。今逐客以资敌国,损民以益仇,内自虚而外树怨于诸侯,求国无危,不可得也。

同类题3

完形填空

    The other day I was talking to a stranger on the bus; he told me that he had a good 1 in Chicago and he wondered if, by any chance, I 2 to know him . For a moment, I thought he might be 3 , but I could tell from the expression on his face that he was not. He was 4. I felt like saying that it was ridiculous (可笑的) to think that out of all the millions of people in Chicago I could possibly have ever bumped into his friend. But, 5, I just smiled and reminded him that Chicago was a very 6 city. He nodded, and I thought he was going to be content to drop the subject and talk about something else. But I was wrong. He was silent for a few minutes, and then he 7 to tell me all about his friend.

    His friend's main 8 in life seemed to be tennis. He was an excellent tennis player, and he even had his own tennis court(网球场). There were a lot of people with swimming 9, yet there were only two people with private tennis court; his friend in Chicago was one of them. I told him that I knew several 10 like that, including my brother, who was doctor in California. He 11 that maybe there were more private courts in the country, than he realized but he did not know of any others. Then he asked me 12 my brother lived in California. When I said Sacramento, he said that was a coincidence(巧合) 13 his Chicago friend spent the summer in Sacramento last year and he lived next door to a 14 who had a tennis court in his backyard. I said I felt that really was a coincidence because my next-door neighbour had gone to Sacramento last summer and had hired the house next to my brother's house. For a moment, we stared at each other, but we did not say anything.

    “Would your friend's name happen(碰巧) to be Roland Kirkwood?” I asked finally. He laughed and said,“Yes. Would your brother's name happen to be Dr Rey Hunter?” It was my 15 to laugh. “Yes,” I replied.