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matter how highly developed the export countries are.
　　C no matter how highly developed the import countries are.
　　D no matter where the country is located.
　　33 The example in the third paragraph concerning Canada and Janpan best illustrates the statement that
　　A a most-favored-nation clause is included in every international trade treaty.
　　B contracting nations give to each other the same rights or concessions as to a third party.
　　C the most-favored-nation status is just applicable to import duties.
　　D Canada must treat Japan fairly by granting it the same benefits as to Korea.
　　34 Concerning the two forms of most-favored-nation treatment, we can see that
　　A the unconditional form of most-favored-nation treatment grants any rights and concessions to another party that demands them.
　　B the conditional form of most-favored-nation treatment is not in any sense desirable in international trade.
　　C The two forms of most-favored-nation treatment exist side by side in international trade practices.
　　D the author is obviously in favor of the unconditional form of most-favored-nation treatment.
　　35 Which of the following titles can best replace the original one?
　　A Decisive and Controversial Tariffs
　　B Import Duties:the Most Important Source of National Income
　　C Protection of Domestic Manufactures
　　D Mutual Benefit in International Trade Treaties
　　第二篇 Putting Plants to Work
　　Using the power of the sun is nothing new. People have had solar-powered calculators and buildings with solar panels for decades. But plants are the real experts: They've been using sunlight as an energy source for billions of years.
　　Cells in the green leaves of plants work like tiny factories to convert sunlight, carbon dioxide, and water into sugars and starches, stored energy that the plants can use. This conversion process is called photosynthesis. Unfortunately, unless you're a plant, it's difficult and expensive to convert sunlight into storable energy. That's why scientists are taking a closer look at exactly how plants do it.
　　Some scientists are trying to get plants, or biological cells that act like plants, to work as miniature photosynthetic power stations. For example, Maria Ghirardi of the National Renewable Energy Laboratory in Golden, Colo. , is working with green algae. She's trying to trick them into producing hydrogen instead of sugars when they perform photosynthesis. Once the researchers can get the algae working efficiently, the hydrogen that they produce could be used to power fuel cells in cars or to generate electricity.
　　The algae are grown in narrow-necked glass bottles to produce hydrogen in the lab. During photosynthesis, plants normally make sugars or starches. "But under certain conditions, a lot of algae are able to use the sunlight energy not to store starch, but to make hydrogen." Ghirardi says. For example, algae will produce hydrogen in an airfree environment. It's the oxygen in the air that prevents algae from making hydrogen most of the time.
　　Working in an airfree environment, however, is difficult. It's not a practical way to produce cheap energy. But Ghirardi and her colleagues have discovered that by removing a chemical called sulfate from the environment that the algae grow in, they will make hydrogen instead of sugars, even when air is present.
　　Unfortunately, removing the sulfate also makes the algae's cells work very slowly, and no