Passage Three
Questions 21 to 25 are based on the following passage.

Humanity uses a little less than half the water available worldwide. Yet occurrences of shortages and droughts (干旱) are causing famine and distress in some areas, and industrial and agricultural by-products are polluting water supplies. Since the world's population is expected to double in the next 50 years, many experts think we are on the edge of a widespread water crisis.

But that doesn't have to be the outcome. Water shortages do not have to trouble the world-if we start valuing water more than we have in the past. Just as we began to appreciate petroleum more after the 1970s oil crises, today we must start looking at water from a fresh economic perspective. We can no longer afford to consider water a virtually free resource of which we can use as much as we like in any way we want.

Instead, for all uses except the domestic demand of the poor, governments should price water to reflect its actual value. This means charging a fee for the water itself as well as for the supply costs.
Governments should also protect this resource by providing water in more economically and environmentally sound ways. For example, often the cheapest way to provide irrigation(灌溉)water in the dry tropics is through small-scale projects, such as gathering rainfall in depressions(凹地) and pumping it to nearby cropland.

No matter what steps governments take to provide water more efficiently, they must change their institutional and legal approaches to water use. Rather than spread control among hundreds or even thousands of local, regional, and national agencies that watch various aspects of water use, countries should set up central authorities to coordinate water policy.

21. What is the real cause of the patential water crisis.
A)Only harf of the world's warter can be used.
B)The world population is inereasing faster and faster.
C)Half of the world's water resources have been seriously polluted.
D)Humanity has not placed officient value on water resources.

22. As indicated in the passage, the water problem _________ .
A)is already serious in certain parts of the world.
B)Has been exaggerated by some experts in the field
C)Poses a challenge to the technology of building reservoirs
D)Is underestimated by government organizations at different levels

23. According to the author, the water price should _______ .
A)be reduced to the minimum
B)stimulate domestic demand
C)correspond to its real value
D)ake into account the occurrences of droughts

24. The author says that in some hot and dry areas it is advisable to _________ .
A)build big lakes to store water
B)construct big pumping stations
C)build small and cheap irrigation systems
D)channel water from nearby rivers to cropland

25. In order to raise the efficiency of the water supply, measures should be taken to ______ .
A)guarantee full protection of the environment
B)centralize the management of water resources
C)increase the sense of responsibility of agencies at all levels
D)encourage local and regional of water resources

Passage Four
Questions 26 to 30 are based on the following passage.

We can see how the product life cycle works by looking at the introduction of instant coffee. When it was introduced, most people did not like it as well as "regular"coffee and it took several years to gain general acceptance (introduction stage). At one point, though, Instant coffee grew rapidly in popularity and many brands were introduced (stage of rapid growth). After a while people became attached to one brand and sales leveled off (stage of maturity). Sales went into a slight decline （衰退）when freeze-dried coffees were introduced (stage of decline).

The importance of the product life cycle to marketers is this: Different stages in the product life cycle call for different strategies. The goal is to extend product life so that sales and profits do not decline. One strategy is called market modification. It means that marketing managers look for new users and market sections. Did you know, for example, that the backpacks that so many students carry today were originally designed for the military?

Market modification also means searching for increased usage among present customers or going for a different market, such as senior citizens. A marketer may re-position the product to appeal to new market sections.

Another product extension strategy is called product modification. It involves changing product quality, features, or style to attract new users or more usage from present users. American auto manufacturers are using quality improvement as one way to recapture world markets. Note, also, how auto manufacturers once changed styles dramatically from year to year to keep demand from falling.

26. According to the passage, when people grow fond of one particular brand of a product, its sales will ____ .
A)decrease gradually         C)improve enormously
B)become unstable            D)remain at the same level

27. The first paragraph tells us that a new product is _____ .
A)usually introduced to satisfy different tastes
B)often more expensive than old ones
C)often inferior to old ones at first
D)not easily accepted by the public

28. Marketers need to know which of the four stages a product is in so as to __________ .
A)work out marketing policies                C)promote its production
B)increase its popularity                    D)speed up its life cycle

29. The author mentions the example of "backpacks"(Line 4, Para.2 ) to show the importance of _______ .
A)increasing usage among students               C)pleasing the young as well as the old
B)exploring new market sections                 D)serving both military and civil needs

30. In order to recover their share of the world market, U.S. auto makers are _______  .
A)improving product quality                     C)re-positioning their product in the market
B)modernizing product style                     D)increasing product features