W: Exercise, exercise, exercise. We hear so much about it these days, yet even the experts can’t agree on which exercises are best. Now some doctors are strongly encouraging arm exercises.M: Arm exercises Is that because our arms are too fat or flabbyW: Actually, that’s not the main reason. They say that arm exercises are an ideal way to become physically fit.M: But don’t arm exercises raise your blood pressureW: That they do. But the article I read mentioned ways to compensate for that.M: HowW: By adding leg exercises, so the arms don’t do all the work. Arm exercises alone aren’t enough to increase metabolism before fatigue sets in it. The more of the body that’s involved in the exercises, the better.M: And in turn, I’m sure that there’s a great chance of losing weight.W: Sounds right to me.M: So what exercises do the experts recommendW: They mentioned quite a few, but some of the more popular ones are cycling with special bicycles that make you use both your arms and legs. And walking vigorously while you wear arm weights.M: I must try that. I like to walk a lot. Which of the following exercises is suggested()
A. Wearing arm weights while you are swimming.
B. Jogging vigorously in one place for a long time.
C. Using bicycles that require you to use both your arms and legs.
D. Walking slowly while swing your arms back and fort
Although the size of the workforce depends a great deal on the size of the total population, there are several other influences which also affect it. The age distribution of the total population has a very (21) effect on the available workforce. If the population has a high (22) of very young people or of (23) too old to work, then the available workforce would be lower than (24) there were an (25) spread age distribution. If the population grows raidly (26) natural increase, i.e., the number of births greatly (27) the number of deaths, then as a total population increases the proportion of the workforce (28) .Sometimes a population is described as aging, (29) means that the birth rate is either falling or growing very slowly, and as people retire (30) the workforce there are insufficient numbers of young people entering it to (31) those who are leaving it. The population is top heavy with older people. So the (32) of the population in the workforce declines when there is (33) a rapid increase in births or a falling birth rate.The age distribution of the population has several important effects on the economy. If the population is aging and there is an increase in the number of people retiring (34) a corresponding increase in the number entering the workforce, this raises the problem of the ability of the economy to provide a (35) level of social services to the retired group. If the (36) are to be cared (37) in special homes or hotels, finance must be (38) for that purpose. If the size of the workforce is small relative (39) the total population, then the government tax receipts are relatively low and either the government has less money available to it or the workforce members have to be (40) more heavily. 25().
A. evenly
B. oddly
C. smoothly
D. decently
In the atmosphere, carbon dioxide acts rather like a one-mirror-the glass in the roof of a greenhouse which allows the sun’s rays to enter but prevents the heat from escaping.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 fuels 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, possibly resulting in an alteration of the 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 only a few degrees of warming: in other words, by a warming on the scale that will possibly take place in the next fifty years from the burning of fuels.Satellite pictures show that large areas of Antarcitic ice are already disappearing. The evidence available suggests that a warming takes 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 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 the most effect on the weatherOn 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 rotated, every 27.5 days, it presents hotter of "colder" face 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 new Ice Age and it is not. One way of solving this theoretical difficulty is to assume a way of thousands of years while the solar effects overcome the inertia (惯性的) of the earth’s climate. If this is right, the warming effect of carbon dioxide might thus be serving a useful counter-balance to the sun’s diminishing heat. On the basis of their models, scientists are of the opinion that ().
A. the climate of the world should be becoming cooler
B. it will take thousands of years for the inertia of the earth’s climate to take effect
C. the man-made warming effect helps to increase the solar effects
D. the new Ice Age will be delayed by the greenhouse effect
安徽的齐云山是我国丹霞地貌中最高的山地。( )
A. 对
B. 错