[阅读理解]

【题干】It's early August and the countryside appears peaceful. Planting has long been
finished and the fields are alive with strong, healthy crops. Soybeans and wheat are
flourishing under the hot summer sun, and the corn, which was“knee-high by the
fourth of July", is now well over six feet tall. Herds of dairy and beef cattle are
grazing peacefully in rolling pastures which surround big, red barns and neat, white
farmhouses. Everything as far. as the eye can see radiates a sense of prosperity.
Welcome to the Midwest - one of the most fertile agricultural regions of the world.
The tranquility of the above scene is misleading. Farmers in the Midwest put in
somc of the longest workdays of any profession in the United States. In addition to
caring for their crops and livestock, they have to keep up with new farming
techniques, such as those for combining soil erosion and increasing livestock
production. It is essential that farmers adopt these advanccs in technology if they
want to continue to meet the growing demands of a hungry world.
Agriculturc is the number one industry in the United States and agricultural
products are the country's leading export. American farmers manage to feed not
only the total population of the United States, but also millions of other people
throughout the rest of the world. Corn and soybean exports alone account for
approximately 75 percent of the amount sold in world markets.
This productivity, however, has its price. Intensive cultivation exposes the
earth to the damaging forces of naturc. Every year wind and water remove tons of
rich soil from the nation's croplands, with the result that soil erosion has become a
national problem concerming everyone from the farmer to the consumer.
Each field is covered by a limited amount of topsoil, the upper layer of earth
which is richest in the nutrient and minerals necessary for growing crops. Ever
since the first farmers arrived in the Midwest almost 200 years ago, cultivation and,
consequently, erosion have been depleting the supply of topsoil. In the 1830s,
nearly two feet of rich, black top soil covered the Midwest. Today the average
depth is only eight inches, and every decade another inch is blown or washed away.
This erosion is steadily decreasing the productivity of valuable cropland. A United
States Agricultural Department survey states that if erosion continues at its present
rate, comn and soybean yields in the Midwest may drop as much as 30 percent over
the next 50 years.

【题目】【阅读理解】4. According to Para. 4______.
A. soil deterioration is becoming a serious problem
B. climate change reduces the area of the croplands
C. customers have to pay more for agricultural products
D. high productivity comes along with damaging forces of nature

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