单选题The atmosphere（）certain gases mixed together in definite proportions.Acomposes ofBis made upCconsists ofDmakesup of
单选题
The atmosphere（）certain gases mixed together in definite proportions.
A
composes of
B
is made up
C
consists of
D
makesup of
参考解析
解析：
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means that every project has a definite beginning and a definite end．A．Project phaseB．UniqueC．TemporaryD．Closure
A greenhouse is a building made of glass which is used for keeping plants when the outside temperature is low. In a similar way there are several gases in the atmosphere which trap(捕捉)the heat produced by the sun and prevent it from escaping. These gases are known as"greenhouse gases"，and the way in which they trap heat in the atmosphere is called the "greenhouse effect". This is not simply air pollution. Most of the main greenhouse gases exist naturally in small amounts in our atmosphere, and without them earth would be 30 degrees colder and human life would not exist. In other words, the greenhouse effect is a natural course which is to some degree helpful to us.The problem is that in the last century and a half, we have been putting too many of these gases into the earth's atmosphere by burning large quantities of coal and oil and by cutting down forests. The rapid increase in greenhouse gases is making the world warmer. The world's temperature has already gone up by half a degree this century, and the sea level has risen by 10 centimetres. If the amount of carbon dioxide(二氧化碳)in the atmosphere doubles, there will probably be a rise in the earth's temperature of between 1 and 4 degrees. This may seem a small increase, but it would be enough to cause major changes in geography and agriculture. Large areas of the world would be flooded, and some areas would become dry and unable to produce crops. It is important, too, to consider that there may be a delay of about 30 years in the greenhouse effect. This means that we are probably experiencing only now the effect of the gases put into the atmosphere before the 1960s. Since then, our use of these gases has greatly increased.1. The"greenhouse effect"means _____.A. the way in which gases are used for keeping plants warmB. a natural course which is some degree helpful to usC. the way"greenhouse gases"trap heat on the earthD. the whole course in which greenhouse gases prevent heat2. If there were no greenhouse effect, _____.A. no plants would grow on our planetB. earth would be thirty degrees colderC. man could not live on the earthD. All of the above answers are correct3. Which of the following is NOT true? _____A. Burning too much coal and oil produces lots of greenhouse gases.B. It has become warmer on the earth now than in the past.C. Gases put into the atmosphere now will affect the earth years later.D. The temperature in a greenhouse is as high as that in the atmosphere.4. Suppose the earth's temperature rose by 3 degrees, _____.A. great harm would be done to mankindB. the sea level would go by 10 centimetresC. all the land in the world would be floodedD. crops would be unable to grow on the earth5. This passage mainly deals with _____.A. the concept(概念)and harm of greenhouse effectB. the relation between greenhouse gases and manC. the concept and change of greenhouse effectD. the effect of the rise of the earth's temperature
He () oil and water, but they (). A、mixed, don’t mixB、mixxed, were not mixxedC、mixed, were not mixingD、mixxed, don’t mix
The conclusion from the study is not definite；it is just______.A．tentativeB．validC．technicalD．thorough
The atmosphere consists of an ocean of gases ______ miles high. A. hundreds B. hundreds of C. of hundreds D. of hundreds of
At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.There could be life on the Mars in the future ifA.it supported life in the pastB.certain gases are used to cool the planetC.the atmosphere can be heated enough to grow simple plantsD.the planet's volcanoes become as active as they were in the past
The atmosphere（）certain gases mixed together in definite proportions.Acomposes ofBis made upCconsists ofDmakesup of
The atmosphere（）certain gases mixed together in definite proportions.A、composes ofB、is made upC、consists ofD、makesup of
单选题We can hardly accept any marks（）or damage（）the cargo.Amixed/toBmixing/toCbeing mixed/forDbeing mixed/of
单选题The atmosphere（）certain gases mixed together in definite proportions.Acomposes ofBis made upCconsists ofDmakes up of
单选题The chemical instructor told the students that heat is _____ whenever certain chemicals are mixed together.AcirculatedBproducedCengagedDmodified
单选题Which substance is NOT considered to be Oil under the pollution prevention regulations? （）APetroleum and fuel oilBSludgeCOil mixed with dredge spoilDOil refuse and oil mixed with wastes
单选题Vapor given off by a flammable liquid will burn when ignited provided（）Athe vapor and air mixture is too richBit is mixed with certain proportions of airCthe vapor is too little compared to the airDit is of heavy toxicity
单选题（）means that every project has a definite beginning and a definite end.AProject phaseBUniqueCTemporaryDClosure
填空题By increasing the levels of greenhouse gases in the atmosphere, human activities are strengthening Earth’s natural greenhouse effect.____
单选题A pumproom is suspected of accumulating gases after a ventilation machinery breakdown. Where should the combustible gas indicator case be placed when testing the pumproom atmosphere for combustible gases? （）AIn the lower level of the pumproomBIn the middle level of the pumproomCIn the upper level of the pumproomDOn the deck outside the pumproom
单选题A definite advantage of using water as a fire extinguishing agent is its characteristic of（）.Aalternate expansion and contraction as water in a liquid state becomes a vaporBabsorption of smoke and gases as water is converted from a liquid to a vaporCrapid contraction as water is converted from a liquid to a vaporDrapid expansion as water absorbs heat and changes to steam
单选题According to the passage, the root cause for weather changes on the earth is ______.Athe atmosphere surrounding the earthBwater from oceans and lakesCenergy from the sunDgreenhouse gases in the sky
单选题（）means that every project has a definite beginning and a definite end.AProjectphaseBUniqueCTemporaryDClosure
单选题Faulty operation of any system is indicated by very definite （）.AsymptomsBsamplesCtracesDtracks
单选题An oxygen indicator can be used to determine if there is（）.Asufficient oxygen in a compartment to support lifeBcombustible gases presentChydrogen gases presentDAll of the above
单选题Certain layers of the atmosphere have special names （）.AwhichindicatedtheircharacterpropertiesBwhosecharacteristicpropertiesareindicatingCwhatcharacterizetheirindicatedpropertiesDthatindicatetheircharacteristicproperties
单选题At ground level, nitrous oxides are bad enough, but when up high, atmospherically they bond with free ions to create dangerous smog particles.Abut when up high, atmospherically theyBhowever, it is in the upper atmosphere in which it mayCbut in the upper atmosphere, theyDhowever, but once in the upper atmosphere it is known toEas in the upper atmosphere they