阅读理解

　　Grasslands need time to rest when cattle and other animals feed on them．Moving animals from one area of pasture(牧场)to another can provide the time needed for new growth．This is called rotational grazing．(循环放牧)

　　Rotational grazing is good for the land and the animals, and it can save money．This form of grazing can reduce the need for pesticide(农药)treatments by reducing the growth of weeds．And it can limit the need for chemical fertilizers by letting animal wastes do the job of natural fertilizer．Rotational grazing can even help prevent wildfires by keeping grasslands in good condition．

　　Letting animals feed continually and intensively(集中地)in the same grazing areas can require costly replanting．Animals eat the most desirable growth first．When that keeps happening, the roots do not have enough time to recover．As a result, less desirable plants may replace them．Intensively used grasslands are also harmed as the soil is continually crushed under the weight of heavy animals．

　　While rotational grazing can save money over time, it also requires planning．And that starts with a good map to mark fences, water supplies and grazing areas．

　　Changing methods of grazing also requires time．Farmers may want to put up electric fences to enclose(圈起)grazing areas, called paddocks．The paddocks will need water．Some farmers design a path for animals from different paddocks to drink from a common watering place．

　　Farmers can start rotational grazing by removing animals from a pasture when the grass is eaten to less that five centimeters．The pasture is then kept empty until the grass grows to more than fifteen centimeters high．

　　Sheep and goats may require special preparations．They may need stronger fences than other animals．And while they eat the grass, they may need guard animals to protect them from animals that would like to eat them．

阅读理解

　　Farmers grow cocoa trees in the shady areas of rainforests near the Earth's equator．These trees can be difficult to grow．They require an exact amount of water, warmth, soil and protection．After about five years, cocoa trees start producing large fruits called pods．The seeds inside these pods are harvested to make chocolate．

　　Today we travel around the world exploring the history of chocolate．Its story begins with a plant whose scientific name, The obroma cocoa, means “food of the gods”．People have been enjoying the rich flavor of chocolate, a product made from this plant．

　　Most people know that chocolate is made from cocoa and that the origins of chocolate can be traced back to Central and South America．For centuries, the natives there regarded cocoa as a gift from the gods．But how did chocolate go from being the food of the gods to being the food of love?

　　Historians believe the Maya of Central America first learned to farm cocoa plants around two thousand years ago．The Maya took the cocoa trees from the rainforests and grew them in their gardens．They cooked the cocoa seeds, and then crushed them into a soft substance．They used the cocoa bean as the main part in a dark, bitter drink that we would call “chocolate”．They believed that chocolate had mystical characteristics－ but cocoa also had commercial(商业的)value．In fact, cocoa beans were used as a form of currency that was worth its weight in gold!

　　The explorer Christopher Columbus brought cocoa seeds to Spain after his trip to Central America in 1502．But the Spanish explorer Conquistador Hernando Cortez was the first European explorer to realize cocoa's commercial possibilities．When he arrived in the New World in 1519, he soon established his own cocoa factory．In 1529, Cortez returned to Spain and introduced chocolate－ as a drink mixed with sugar, vanilla, and cinnamon－to European society．

　　The wealthy people of Spain first enjoyed a sweetened type of the chocolate drink．Later, the popularity of the drink spread throughout Europe．The English, Dutch and French began to plant cocoa trees in their own countries．Chocolate remained a drink that only wealthy people could afford to drink until the eighteenth century．During the period known as the Industrial Revolution, new technologies helped make chocolate less costly to produce．

　　It caught on－especially with the noble people, who enjoyed hot chocolate as an aphrodisiac(a kind of medicine)．As its popularity spread, people found new ways to make and use chocolate．These days, chocolate is enjoyed as both a tasty treat and a romantic gift everywhere．