【正确答案】 C

【答案解析】[解析] 12-17 When European explorers first approached the coast of North America, even before their ships landed, the first thing they noticed was the pungent aroma carried to the ships by the offshore breezes. Some sea captains thought this aroma was the scent of the valuable Oriental spices that had prompted their voyages of exploration. But in fact, the agreeable smells didn't come from spices; they came from the lush vegetation of the North American forests. The fragrance came from the blossoms of numerous trees and from the volatile oils in pine sap. Pine sap is a resinous fluid that pine trees put out to heal wounds caused by wind, fire, and lightning, and also to protect the pine tree's seeds. Pine sap was a valuable commodity to the sailors who explored the coast. The smell of pine meant there was an abundant supply of what were known as naval stores--pitch and pine tar. Pitch and pine tar were thick, sticky, semi-solid substances that were made by distilling pinewood. Sailors used naval stores for caulking and waterproofing their wooden ships, which kept them seaworthy. The Europeans found fragrant trees all along the Atlantic coast, from Massachusetts in the north to Florida in the south. Everywhere along the coast, the air was filled with the strong perfume of the flowering dogwood. The Native Americans already knew about the medicinal properties of the dogwood, and they used its bark and roots to treat malaria and other fevers. They brewed the aromatic bark into a bitter, astringent tea. European settlers also used the dogwood to relieve attacks of malaria. They soaked the dogwood bark in whiskey and drank the strong infusion. This was before they knew about quinine from South America, and before quinine became available. In the south, probably the best-known aromatic tree was the sassafras. The sassafras is a fast-growing tree, a member of the laurel family. Like the other fragrant laurels--cinnamon, bay, and camphor--sassafras is noted for its aromatic bark, leaves, roots, flowers, and fruit. I have a sassafras twig with me here, which I'll pass around so you can all enjoy its smell. Just give it a small scrape with your thumbnail to release the scent. I think you'll find it strong but pleasant. The Choctaw Indians used powdered sassafras leaves as a spice. Other Native American tribes used sassafras tonic as a cure for everything from fever to stomachache. News of this wonder tree reached Europe in the sixteenth century by way of the French and the Spanish, and sassafras was one of the first exports from North America to Europe. It sold for a high price on the London market, which sort of inspired other English explorers to ... um ... seek their fortunes in the North American colonies. For centuries, sassafras enjoyed a fantastic reputation as a cure for almost every disease. Maybe you've heard of the medicinal spring tonic of the old days. Well, sassafras was a main ingredient in spring tonic--the stuff pioneer parents gave their kids. My grandmother had to take spring tonic that her grandmother made from sassafras. Sassafras leaves, bark, and roots used to provide the flavoring for root beer and chewing gum. Sassafras was also used in soaps and perfumes. However, in the 1960s, the United States Food and Drug Administration found sassafras oil to be a potential carcinogen for humans because it caused cancer in rats. Since that time, sassafras has been banned for human consumption. No one really knows just how harmful it is to human beings, but some studies show that one cup of strong sassafras tea contains more than four times the amount of the volatile oil safrole that is hazardous to humans if consumed on a regular basis. The speaker says: When European explorers first approached the coast of North America the first thing they noticed was the pungent aroma...; ... the agreeable smells didn't come from spices; they came from the lush vegetation of the North American forests.