问题 填空题

干冰是固态的二氧化碳,在常温下易升华,右图是干冰升华时的情景,根据图中信息,从“

”这一角度分析干冰具有的性质和用途

(1)干冰升华时           (填“吸收”或“放出”)大量热,因此可作致冷剂

或用于人工降雨。

(2)干冰转化成二氧化碳气体后能参与绿色植物的光合作用,绿色植物通过光合作用吸收二氧化碳,同时放出            (填名称)。

(3)将干冰转化成的二氧化碳气体通入紫色石蕊试液,可看到_____           的现象,原因是:(用化学方程式表示)__________________,加热后可看到____________ __的现象。

(4)大气中二氧化碳等气体的含量过高,容易造成“温室效应”.为了减缓“温室效应”,以下建议中合理的是          (填序号)。

①开发太阳能、水能、风能、地热等能源;②减少化石燃料的使用;

③大量植树种草,禁止乱砍滥伐。

( 5 )近年来大气中二氧化碳含量不断上升的主要原因是                 

( 6 )下列变化中,对维持大气中二氧化碳气体总量平衡至关重要的是        (填序号)

A.CO2+H2O=H2CO3

B.6CO2+6H2OC6H12O6+6O2

C.CO2+C2CO

D.CO2+2NaOH=Na2CO3+H2O

答案

(1)干冰升华时      吸收    (填“吸收”或“放出”)

(2)同时放出     氧气   (填名称)。

(3)可看到_ 溶液变红 的现象,原因是:(用化学方程式表示) CO2+H2O=H2CO3_,

加热后可看到___溶液由红色变成紫色_的现象。

(4)合理的是      ①②③   (填序号)。

( 5 )主要原因是  大量使用化石燃料

( 6 )至关重要的是    B   (填序号)

(1)干冰升华易吸热,可用于人工降雨,故填:吸热;

(2)植物通过光合作用吸收二氧化碳生成氧气,故填:氧气;

(3)二氧化碳能与水反应生成碳酸,碳酸呈酸性,能使石蕊试液变红,碳酸不稳定,受热易分解生成二氧化碳和水,酸性消失,故填:变红,CO2+H2O=H2CO3,溶液由红色变成紫色;

(4)①开发太阳能、水能、风能、地热等能源能减少二氧化碳的排放,有利于减缓温室效应,②减少化石燃料的使用能减少二氧化碳的排放,有利于减缓温室效应,③大量植树种草,禁止乱砍滥伐,能增加二氧化碳的吸收,有利于减缓温室效应,故填:①②③;

(5)近年来大气中二氧化碳含量不断上升的主要原因是化石燃料的大量使用,故填:大量使用化石燃料;

(6)自然界中维持二氧化碳平衡的主要反应是植物的光合作用,故填:B.

单项选择题
阅读理解

阅读理解。

     The US Department of Labor statistics show that there is an oversupply of college trained

workers and that this oversupply is increasing. Already there have been more than enough

teachers, engineers, physicists, aerospace experts, and other specialists. Yet colleges and

graduate schools continue every year to turn out highly trained people to compete for jobs

that aren't there. The result is that graduates cannot enter the professions for which they were

trained and must take temporary jobs which do not require a college degree.

     On the other hand, there is a great need for skilled workers of all sorts: carpenters,

electricians, mechanics, plumbers, TV repairmen. These people have more work than they

can deal with, and their annual incomes are often higher than those of college graduates. The

old gap that white-collar workers make a better living than blue collar workers no longer holds

true. The law of supply and demand now favors the skilled workmen.

     The reason for this situation is the traditional myth that college degree is a passport to a

prosperous future. A large part of American society matches success in life equally with a

college degree. Parents begin indoctrinating (灌输) their children with this myth before they

are out of grade school. High school teachers play their part by acting as if high school

education were a preparation for college rather than for life. Under this pressure the kids fall

in line. Whether they want to go to college or not doesn't matter. Everybody should go to

college, so of course they must go. And every year college enrollments go up and up, and

more and more graduates are overeducated for the kinds of jobs available to them.

     One result of this emphasis on a college education is that many people go to college who

do not belong there. Of the sixty percent of high school graduates who enter college, half of

them do not graduate with their class. Many of them drop out within the first year. Some

struggle on for two or three years and then give up.

1. It's implied but not stated in the passage that ______.

A. many other countries are facing the same problem

B. fewer students will prefer to go to college in the future

C. the law of supply and demand has a strong effect on American higher education

D. white-collar workers in the US used to make more money than blue-collar workers

2. Which of the following is NOT a reason why the number of college students goes up every year?

A. Many parents want their children to go to college.

B. Every young man and woman wants to go to college.

C. High school teachers urge their students to go to college.

D. Many people believe that the only way to success is a college education.

3. By saying that "many people go to college who do not belong there", the author means that______.

A. many people who do not have enough money go to college

B. many people who go to college have their hopes destroyed

C. many people who go to college drop out within the first year

D. many people who are not fit for college education go to college

4. We can infer from the passage that the author believes that ______.

A. college education is a bad thing

B. every young man and woman should go to college

C. people with a college education should receive higher pay

D. fewer people should go to college while more should be trained for skilled jobs