科学家们对生活在海洋中的各种各样的鱼进行分析研究，发现鱼鳃上都有一种能排除盐分的特殊组织，叫“氯化物分泌细胞”。正是这个组织，使得海鱼长期生活在海水中而肉却不咸。这是对各种各样的海鱼进行认识而得出的普遍性结论。这一认识不是一次就能够完成的。上述事例说明                                                                      (　　)

①对一事物的正确认识要经过多次反复　           ②对各种鱼的认识是一种完全归纳法　

③对复杂事物的认识要反复地发散——聚合——发散——聚合　④人们可以穷尽对事物的认识

阅读下列短文，从每题所给的四个选项 A、B、C、D中选出最佳选项。

C

    There are over 800 boarding schools in the UK with students from home and foreign countries. Boarding schools started hundreds of years ago in the country. But the earliest boarding schools were set up for white, rich boys only. Now both boys and girls can go to boarding schools from the age of 7 to 18.

    What to do?

    In the UK, boarding schools have three terms in a school year, with about 13 weeks in each term. Students study and live together. They can't go outside if they are not allowed to. In some schools, each student has his or her subject plan. Besides the usual classrooms and laboratories, the boarding schools have lots of other facilities for their students, including music rooms, boats, swimming pools, cinemas and theatres. Most boarding schools have a "light-out" time. So when it's time to go to bed, all the lights in the bedrooms are turned off. There are house-masters to take care of students all the time, especially after school hours.

    What to wear?

Nearly all students at boarding schools wear a school uniform. Boys usually wear a shirt and a tie, and girls wear a white blouse, sometimes also a tie and a skirt. As students get older, the rules become less strict.

    ____________?

    In the UK, boarding schools provide students with delicious food. They can choose to have a full English breakfast or simply bread. They can also choose between a meal with no meat and another meal at lunch and dinner. And there is always self-service for salad (沙拉), other side dishes and a dessert. Students can also make themselves something to eat at any time in a kitchen, or drink tea or have a snack between meals.

I became more and more excited, trying to work out ____ Mom was taking us on holiday.

阅读丰子恺先生的《蜜蜂》一文，完成下列小题。

       ①正在写稿的时候，耳朵近旁觉得有“嗡嗡”之声，间以“得得”之声。因为文思正畅快，只管看着笔底下，无暇抬头来探究这是什么声音。然而“嗡嗡”，“得得”，也只管在我耳旁继续作声，不稍间断。过了几分钟之后，它们已把我的耳鼓刺得麻木，在我似觉这是写稿时耳旁应有的声音，或者一种天籁，无须去探究了。

       ②等到文章告一段落，我放下自来水笔，照例伸手向罐中取香烟的时候，我才举头看见这“嗡嗡”“得得”之声的来源。原来有一只蜜蜂，向我案旁的玻璃窗上求出路，正在那里乱撞乱叫。

       ③我以前只管自己的工作，不起来为它谋出路，任它乱撞乱叫到这许久时光，心中觉得有些抱歉。然而已经挨到现在，况且一时我也想不出怎样可以使它攒得出去的方法，也就再停一会儿，等到点着了香烟再说。

       ④我一边点香烟，一旁观它的乱撞乱叫。我看它每一次攒，先飞到离玻璃一二寸的地方，然后直冲过去，把它的小头在玻璃上“得，得”地撞两下，然后沿着玻璃“嗡嗡”地向四处飞鸣。其意思是想在那里找一个出身的洞。也许不是找洞，为的是玻璃上很光滑，使它立脚不住，只得向四处乱舞。乱舞了一回之后，大概它悟到了此路不通，于是再飞开来，飞到离玻璃一二寸的地方，重整旗鼓，向玻璃的另一处地方直撞过去。因此“嗡嗡”“得得”，一直继续到现在。

       ⑤我看了这模样觉得非常可怜。求生活真不容易，只做一只小小的蜜蜂，为了生活也须碰到这许多钉子。我诅咒那玻璃，它一面使它清楚地看见窗外花台里含着许多蜜汁的花，以及天空中自由翱翔的同类，一面又周密地拦阻它，永远使它可望而不可即。这真是何等恶毒的东西！

       ⑥因了诅咒玻璃，我又羡慕起物质文明未兴时的幼年生活的诗趣来。我家祖母年年养蚕。每当蚕宝宝上山的时候，堂前装纸窗以防风。为了一双燕子常要出入，特地在纸窗上开一个碗来大的洞，当作燕子的门，那双燕子似乎通人意的，来去时自会把翼稍稍敛住，穿过这洞。这般情景，现在回想了使我何等憧憬？假如我案旁的窗不用玻璃而换了从前的纸窗，我们这蜜蜂总可攒得出去。即使撞两下，也是软软地，没有什么苦痛。求生活在从前容易得多，不但人类社会如此，连虫类社会也如此。

       ⑦我点着了香烟之后就开始为它谋出路。但这是一件很不容易的事。叫它不要在这里钻，应该回头来从门里出去，它听不懂我的话。用手硬把它捉住了到门外去放，它一定误会我要害它，会用螯反害我，使我的手肿痛的不能工作。除非给他开窗；但是这扇窗不容易开，窗外堆叠着许多笨重的东西，须得先把这些东西除去，方可开窗。这些笨重的东西不是我一人之力所能除去的。

       ⑧于是我起身来请同室的人帮忙，大家合力除去窗外的笨重的东西，好把窗开开，让我们这蜜蜂得到出路。但是同室的人大家不肯，他们说，“我们做工都很疲倦了，那有余力去搬重物而救蜜蜂呢？”

       ⑨忽然门里走进一个人来和我说话。为了不能避免的事，我立刻被他拉了一同出门去，就把蜜蜂的事忘却了。等到我回来的时候，这蜜蜂已不见。不知道是飞去了，被救了，还是撞杀了。

如图，直线y=kx与双曲线y=﹣ $\frac{2}{x}$ 交于A（x₁，y₁），B（x₂，y₂）两点，则2x₁y₂﹣8x₂y₁的值为（   ）