问题 综合

    我国土壤污染总体形势相当严峻,土壤深度酸化、盐渍化,砷、汞、铅、镉等重金属含量较大,农药等有机污染物残留严重,这对农业生产的可持续发展和人类健康安全造成了威胁。读图回答下列问题。

(1)过量使用化肥是导致土壤污染的主要原因之一,过量使用化肥还会导致________________等危害。

(2)各种污染物进入土壤并积累到一定程度,超出土壤自净能力后,就会造成土壤污染。治理土壤污染,必须坚持__________的原则,首先要控制和消除各种__________;其次是提高土壤自净能力。

(3)从图中可以看出,土壤污染物的来源主要有哪些?

___________________________________________________________________________________________

(4)对于受重金属等污染的土壤,试说出防治的根本方法。

___________________________________________________________________________________________

答案

(1)土壤物理状况改变,土壤肥力下降

(2)以预防为主、防治结合;土壤污染源

(3)农药、化肥、垃圾、污泥、汽车尾气、污水灌溉、粉尘沉降。(3点即可)

(4)挖去受污染的土层,换上新土,以根除污染物。

阅读理解

Every autumn, as families across the United States get ready to send their kids to college, the economics of higher education receive renewed attention. College is expensive and becoming more so in the U. S. The situation raises two questions: Why does it cost so much, and how can students and their families afford it?

Several studies published in the past few weeks reflect on these questions. The findings provide comfort to poor families.

First, it appears that only the minority actually pay the "high price". A study by the US Education Department's National Center for Education Statistics found that 55 percent of college students last year received some forms of help--scholarships, loans(贷款)or jobs.

Other factors are also at work. The government has increased the size of its grants (补助金)to lower-income students. Grants, unlike loans, don't have to he repaid and are awarded only to college students who have not earned a bachelor's or professional degree.

At the same time, most colleges are spending more on undergraduate education than they are collecting in tuition fees. A study, which is part of the Williams College Project on the Economics of Higher Education, reaches the conclusion that on average colleges “subsidize (赞助)” their students. The results of these studies, however, leave unanswered the questions of whether educational costs are higher than they need to be. Some experts argue that much of the college cost results from educational competition for fame, students and facilities.

This puts upward pressure on tuition, hut many colleges feel that good fame will enable them to attract students even if they charge them more.

Therefore, until something important changes in the marketplace, costs seem likely to continue rising. And American families will continue to beat down the doors of the high price "college in the end.

小题1: From the fourth paragraph of the passage we can conclude that _______.

A.American families earn only a little money every year

B.American families pay little attention to education

C.American students often have to stop their studies

D.American colleges have different ways to help poor students小题2: In the writer's opinion, for students from lower-income families, the best way is ________.

A.to find a good job and make money

B.to borrow money from the banks

C.to ask for grants

D.to borrow money from friends小题3: It can be inferred that in America _______.

A.famous colleges only accept rich students.

B.famous colleges charge their students more money

C.the government spends little money on education

D.families often break the doors of colleges小题4: The writer of this passage seems to hold the opinion that _______.

A.college fees rise too fast for poor families.

B.poor people should borrow money from banks

C.poor people don’t need to send their children to college

D.colleges should get more money to improve themselves

单项选择题 A1型题