相关试题
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.On Venus there is a lot of__________.查看材料
A．waterB．carbon dioxideC．carbon monoxideD．oxygen
Such animals as South China tigers are believed __________ ., for we've had no track of them for ages.
A．becoming extinctB．to become extinctC．to have been extinctD．having been extinct
Passage 2If the population of the earth goes on increasing at its present rate, there will eventually not be enough resources left to sustain life on the planet. By the middle of the 21st century, if present trends continue, we will have used up all the oil that drives our cars, for example. Even if scientists develop new ways of feeding the human race, the crowded conditions on earth will make it necessary for us to look for open space somewhere else. But none of the other planets in our solar system are capable of supporting life at present. One possible solution to the problem, however, has recently been suggested by an American scientist, Professor Carl Sagan.Sagan believes that before the earth's resources are completely exhausted it will be possible to change the atmosphere of Venus and so create a new world almost as large as earth itself. The difficulty is that Venus is much hotter than the earth and there is only a tiny amount of water there.Sagan proposes that algae organisms, which can live in extremely hot or cold atmospheres and at the same time produce oxygen, should be bred in conditions similar to those on Venus. As soon as this has been done, the algae will be placed in small rockets. Spaceships will then fly to Venus and fire the rockets into the atmosphere. In a fairly short time, the algae will break down the carbon dioxide into oxygen and carbon.When the algae have done their work, the atmosphere will become cooler, but before man can set foot on Venus it will be necessary for the oxygen to produce rain. The surface of the planet will still be too hot for men to land on it but the rain will eventually fall and in a few years something like earth will be reproduced on Venus.Man can eventually land on Venus only when__________.查看材料
A．the algae have done their workB．the atmosphere becomes coolerC．there is oxygenD．it rains there
The ambiguity in "My friend drove me to the bank." is caused by__________.
A．lexical itemsB．a grammatical structureC．homonymyD．polysemy
Teaching activities must be based on the students' cognitive development level and theexistingexperiencedknowledge,thus,students'personal knowledge,students'Lifeworld and__________ are also the important curriculum resources except textbook.
A．game activitiesB．labour activitiesC．attitudesD．direct experience
最新解答的试题
付款人在进行付款时无（）
A.形式审查义务
B.实质审查义务
C.附带审查义务
D.票据外有关事项的审查义务
根据《公司法》的规定,有限责任公司下列人员中,可以提议召开股东会临时会议的是()。
A.总经理B.人数过半数的股东C.监事会主席D.人数为半数的董事
关于股份有限公司中的监事会，下列说法错误的是()
A.监事会负责提议聘请或更换外部审计机构B.监事会主席和副主席由全体监事过半数选举产生C.监事会中的职工代表的比例不得低于三分之一D.监事会应至少每6个月召开一次会议
阿里巴巴提供了“企业名称认证”“企业身份认证”不同种类的认证,可以根据自身的
