填空题
[听力原文]11-15
In the past, the United States was a nation of farmers. Most of the farms were large enough for one family to take care of. They were usually between 100 and 200 acres in size.
Nowadays, however, business methods have been applied to U.S. agriculture. Chemicals help to keep the soil rich, and machines do a great deal of hard work. Nevertheless, hand labor is still necessary for picking many fruits and vegetables. Workers from other countries go from place to place to pick the crops that are ripe. They make up an agricultural labor force, while management consists of owners and managers. Today, many of them have college degrees and operate farms like corporations. As a result, fewer people now turn out more agricultural products than ever before.