问题 问答题 简答题

赤潮和水华

①本为自然现象:

赤潮(red tide)是海洋中某些微小(2-20微米)的浮游藻类、原生动物或更小的细菌,在满足一定的条件下爆发性繁殖或突然性聚集,引起水体变色的一种自然生态现象。

"水华"(water blooms)是一种在淡水中的自然生态现象,只是仅由藻类引起的,如蓝藻(严格意义上应称为蓝细菌)、绿藻、硅藻等。"水华"发生时,水一般呈蓝色或绿色。这两种在自然界就有的赤潮和"水华

"现象,在我国古代历史上就有记载。在自然界中它们很快消失,并没有给水产动物和人类带来危害。

②发展为灾害:由于人类经济的发展,对大自然造成了许多干扰,最主要的是N、P营养成分的增加,造成淡水、海水的富营养化,为水中这些微小生物的爆发性生长提供了十分有利的条件。在赤潮消失期,赤潮生物大量死亡和分解,耗尽了水中的溶解氧,分解物产生大量的有害气体,恶臭难闻,严重威胁海洋养殖业和

旅游业的发展。同样地,淡水中富营养化后,"水华"频繁出现,面积逐年扩散,持续时间逐年延长。太湖、滇池、巢湖、洪泽湖都有"水华",就连流动的河流,如长江最大支流----汉江下游汉口江段中也出现"水华"。淡水中"水华"造成的最大危害是:饮用水源受到威胁,藻毒素通过食物链影响人类的健康,蓝藻"水华

"的次生代谢产物MCRST能损害肝脏,具有促癌效应,直接威胁人类的健康和生存。由此可见,一个是海洋中,另一个是淡水中;一种是某些微小(2-20微米)的浮游藻类、原生动物或更小的细菌引起水体变色,另一种是仅由藻类引起的,如蓝藻(严格意义上应称为蓝细菌)、绿藻、硅藻。

阅读完上面的材料结合学过的知识回答以下问题。

常见的赤潮有哪些?

答案

参考答案:常见的赤潮:由夜光虫引起的粉红色的赤潮;由某些双鞭毛虫引起的绿色的赤;:由某些硅藻引起的红褐色赤潮;由蓝藻的淡红发束毛藻引起的黄褐色赤潮。

单项选择题

Passage Three

Mary Barton, particularly in its early chapters, is a moving response to the suffering of the industrial worker in the England of the 1840’s. What is most impressive about the book is the intense and painstaking effort made by the author, Elizabeth Gaskell, to convey the experience of everyday life in working-class homes. Her method is partly documentary in nature: the novel includes such features as a carefully annotated reproduction of dialect, the exact details of food prices in an account of a tea party, an itemized description of the furniture of the Bartons living room, and a transcription (again annotated) of the ballad "The Oldham Weaver". The interest of this record is considerable, even though the method has a slightly distancing effect.

As a member of the middle class, Gaskell could hardly help approaching working-class life as an outside observer and a reporter, and the reader of the novel is always conscious of this fact. But there is genuine imaginative re-creation in her accounts of the walk in Green Heys Fields, of tea at the Bartons house, and of John Barton and his friend’s discovery of the starving family in the cellar in the chapter "Poverty and Death". Indeed, for a similarly convincing re-creation of such families’ emotions and responses (which are more crucial than the material details on which the mere reporter is apt to concentrate) , the English novel had to wait 60 years for the early writing of D. H. Laurence. If Gaskell never quite conveys the sense of full participation that would completely authenticate this aspect of Mary Barton, she still brings to these scenes an intuitive recognition of feelings that has its own sufficient conviction.

The chapter "Old Alice’s History" brilliantly dramatizes the situation of that early generation of workers brought from the villages and the countryside to the urban industrial centers. The account of Job Legh, the weaver and naturalist who is devoted to the study of biology, vividly embodies one kind of response to an urban industrial environment: an affinity for living things that hardens, by its very contrast with its environment, into a kind of crankiness. The early chapters—about factory workers walking out in spring into Green Heys Fields; about Alice Wilson, remembering, in her cellar the twig-gathering for brooms in the native village that she will never again see; about Job Legh, intent on his impaled insects—capture the characteristic responses of a generation to the new and crushing experience of industrialism. The other early chapters eloquently portray the development of the instinctive cooperation with each other that was already becoming an important tradition among workers.

According to the passage, Mary Barton and the early novels of D. H. Lawrence share which of the following ?()

A.Depiction of the feelings of working-class families

B.Documentary objectivity about working-class circumstances

C.Richly detailed description of working-class adjustment to urban life

D.Imaginatively structured plots about working-class characters

单项选择题 A1/A2型题