问题 问答题

(1)请你帮他继续设计:把小卵石、活性炭、石英沙三种材料放置在装置相应的位置以获得较好的净水效果,则图中的①②③位置放置的材料依次是______.

(2)活性炭的作用是______.

(3)若在实验室中进行过滤操作,发现滤液浑浊,则可能的原因是______、______.

(4)应如何处理上述浑浊滤液______.

(5)应用改进后的装置过滤,得到了澄清透明的水,该同学兴奋地说:我终于制得了纯净水!对此,小明认为该同学得到的不是纯净水,请你简述小明的理由:______.

答案

(1)小卵石能除去较大的固体颗粒,石英砂能除去较小的固体颗粒,活性炭能吸附色素和异味.顺序应该是小卵石,石英砂,活性炭.

(2)由于活性炭有吸附性,在净化水时活性炭的作用是吸附作用.

(3)在过滤时,发现滤液浑浊,可能的原因有:滤纸破损、液面高于滤纸边等.

(4)上述浑浊滤液重新过滤.

(5)该同学得到的不是纯净水,原因是:上述操作未能除去可以溶于水的杂质.

故答为:(1)小卵石、石英沙、活性炭;(2)吸附作用;(3)滤纸破损,液面高于滤纸边缘;(4)重新过滤;(5)上述操作未能除去可以溶于水的杂质.

选择题
单项选择题

It is simple enough to say that since books have classes -- fiction, biography, poetry -- we should separate them and take from each what it is right and what should give us. Yet few people ask from books what can give us. Most commonly we come to books with blurred and divided minds, asking of fiction that it shall be true, of poetry that it shall be false, of biography that it shall be flattering, of history that it shall enforce our own prejudices. If we could banish all such preconception when we read, that would be an admirable beginning. Do not dictate to your author; try to become him. Be his fellow-worker and accomplice. If you hang back, and reserve and criticize at first, you are preventing yourself from getting the fullest possible value from what you read. But if you open your mind as widely as possible, then signs and hints of almost imperceptible fineness, from the twist and turn of the first sentences, will bring you into the presence of a human being unlike any other. Steep yourself in this, acquaint yourself with this, and soon you will find that your author is giving you, or attempting to give you, something far more definite. The 32 chapters of a novel -- if we consider how to read a novel first -- are an attempt to make something as formed and controlled as a building: but words are more impalpable than bricks; reading is a longer and more complicated process than seeing. Perhaps the quickest way to understand the elements of what a novelist is doing is not to read, but to write; to make your own experiment with the dangers and difficulties of words. Recall, then, some event that has left a distinct impression on you -- how at the comer of the street, perhaps, you passed two people talking. A tree shock; an electric light danced; the tone of the talk was comic, but also tragic; a whole vision, an entire conception, seemed contained in that moment.
But when you attempt to reconstruct it in words, you will find that it breaks into a thousand conflicting impressions. Some must be subdued; others emphasized; in the process you will lose, probably, all grasp upon the emotion itself. Then turn from your blurred and littered pages to the opening pages of some great novelist -- Defoe, Jane Austen, Hardy. Now you will be better able to appreciate their mastery. It is not merely that we are in the presence of a different person -- Defoe, Jane Austen, or Thomas Hardy -- but that we are living in a different world. Here, in Robinson Crusoe, we are trudging a plain high road; one thing happens after another; the fact and the order of the fact is enough. But if the open air and adventure mean everything to Defoe, they mean nothing to Jane Austen. Here is the drawing-room, and people talking, and by the many mirrors of their talk revealing their characters. And if, when we have accustomed ourselves to the drawing-room and its reflections, we turn to Hardy, we are once more spun around. The moors are round us and the stars are above our heads. The other side of the mind is now exposed -- the dark side that comes uppermost in solitude, not the light side that shows in company. Our relations are not towards people, but towards Nature and destiny. Yet different as these worlds are, each is consistent with itself. The maker of each is careful to observe the laws of his own perspective, and however great a strain they may put upon, they will never confuse us, as lesser writers so frequently do, by introducing two different kinds of reality into the same book. Thus to go from one great novelist to another -- from Jane Austen to Hardy, from Peacock to Trollope, from Scott to Meredith -- is to be wrenched and uprooted; to be thrown this way and then that. To read a novel is a difficult and complex art. You must be capable not only of great fineness of perception, but of great boldness of imagination if you are going to make use of all that the novelist -- the great artist -- gives you.

From the passage we learn that ______.

A.Jane Austen always described the characters’ living room in her novels

B.Hardy tried to reveal the relationship between Nature and destiny

C.Defoe reflected the dark side of society

D.great writers sometimes confuse their readers