摘要: take effect生效.奏效

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D

  In the atmosphere,carbon dioxide actd rather like a one-way mirror or the glass in the roof of a greenhouse which allows the sun's rays to enter but prevents the heat from excaping.

  According to a weather expert's prediction,the atmosphere will be 3 warmer in the year 2050 than it is today, if man continues to burn luels at the present rate. If this warming up took place,the ice caps in the poles would begin to melt,thus raising sea level several meters and severely flooding coastal cities.Also,the increase in atmospheric temperature would lead to great changes in the climate of the northern hemisphere(半球),psooicbly resulting in an alteration of earth's chief food growing zones.

  In the past,concern about a man - made warming of the earth has concentrated on the Arctic because the Antarctic is much colder and has a much thicker ice sheet.But the weather experts are now paying more attention to West Antarctic,which may be affected by a warming on the scale that will possibly take place in the next fifty years from on burning of fuels.

  Satellite pictures showthat large areas of Antarctic ice are already disappearing.The evidence available suggests that a warming has taken place.This fits the theory that carbon dioxide warms the earth.

  However,most of the fuel is burnt in the northern hemisphere,where temperatures seem to be falling.Scientists conclude,therefore,that up to now natural influences on the weather have exceeded those caused by man.The question is:Which natural cause has most effect on the weather?

  One possibility is the variable behavior of the sun.Astronomers at one research station have studied the hot spots and cold spots(that is,the relatively less hot spots) on the sun. As the sun rotates(旋转),every 27.5 days,it presents hotter or colder faces to the earth,and different aspects to different parts of the earth.This seems to have a considerable effect on the distribution of the earth's atmospheric pressure,and consequently on wind circulation.The sun is also variable over a long term:its heat output goes up and down in cycles,the latest trend being downward.

  Scientists are now finding mutual relations between models of solar weather interactions and the actual climate over many thousands of years ,including the last Ice Age.The problem is that the models are predicting that the world should be entering a new Ice Age and it is not.

  One way of solving this theoretical difficulty is to assume a delay of thousands of years while the solar effects overcome the inertia(不活动,惰性) of the earth's climate.If this is right,the warming effect of carbon dioxide might thus be serving as a useful counter balance to the sun's diminishing heat.

  68.It can be concluded that a concentration of carbon dioxide in the atmosphere would ___.

   A.mean a warming - up im the Arctic

   B.raise the temperature of the earth's surface

   C.prevent the sun's rays from reaching the earth's surface

   D.account for great changes in the climate in the northern hemiphere

  69.Although the fuel consumption is greater in the northern hemisphere,temperatures there seem to be falling.This is _______.

   A.mainly because the levels of carbon dioxide are rising

   B.partly due to variations in the output of solar energy

   C.possibly because the ice caps in the poles are melting

   D.exclusively due to the effect of the inertia of the earth's climate

  70.On the basis of their models,scientists are of the opinion that ________.

   A.the climate of the world should be becoming cooler

   B.the new Ice Age will be delayed by the greenhouse effect

   C.the man - made warming effect helps to increase the solar effects

   D.it will take thousands of years for the inertia of the earth's climate to take effect

 

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Few laws are so effective that you can see results just days after they take effect. But in the nine days since the federal cigarette tax more than doubled—to $1. 01 per pack—smokers have jammed telephone “quit lines” across the country seeking to kick the habit.  
This is not a surprise to public health advocates. They’ve studied the effect of state tax increases for years, finding that smokers, especially teens, are price sensitive. Nor is it a shock to the industry, which fiercely fights every tax increase.  
The only wonder is that so many states insist on closing their ears to the message. Tobacco taxes improve public health, health, they raise money and most particularly, they deter people from taking up the habit as teens, which is when nearly all smokers are addicted. Yet the rate of taxation varies widely. 
In Manhattan, for instance, which has the highest tax in the nation, a pack of Marlboro Light Kings cost $10.06 at one drugstore Wednesday. Charleston, S, C., where the 7-cent-a-pack tax is the lowest in the nation. The price was $4. 78.  
The influence is obvious.  
In New York, high school smoking hit a new low in the latest surveys—13.8%, far below the national average. By comparison, 26% of high school students smoke in Kentucky, Other low-tax states have similarly depressing teen-smoking records.  
Hal Rogers, Representative from Kentucky, like those who are against high tobacco taxes, argues that the burden of the tax falls on low-income Americans “who choose to smoke.”  
That’s true, But there is more reason in keeping future generations of low-income workers from getting hooked in the first place, As for today’s adults, if the new tax drives them to quit, they will have more to spend on their families, cut their risk of cancer and heart disease and feel better.  
67. The text is mainly about___________.  
A. the price of cigarettes                       B. tie rate of teen smoking  
C. the effect of tobacco tax increase              D. the differences in tobacco tax rate  
68. What does the author think is a surprise?  
A. Teen smokers are price sensitive.  
B. Some states still keep the tobacco tax low.  
C. Tobacco taxes improve public health.  
D. Tobacco industry fiercely fights the tax rise.  
69. The underlined word "deter” in Paragraph 3 most probably means      .  
A. discourage    B. remove    C. benefit      D. free Ks5u
70. Rogers’ attitude towards the low-income smokers might be that of     .  
A. tolerance   B. unconcern    C. doubt   D. concern  

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