四六级考试

【单选题】Passage Two
Questions 30 to 32 are based on the passage you have just hearD、A、To kill the insects when they are eggs.
B、To slow down the growth of insect eggs.
C、To make the crops look better.
D、To preserve the harvests for sale.
网考网参考答案：D
网考网解析：
[解析] 30-32 (30) Airtight plastic bags can help farmers protect their harvests without the use of harmful chemicals. These bags are designed to keep air out of crops in storage. They are a simple way to fight insects and keep food fresh. Farmers can lose much of the harvest to insects called seed beetles. These grow from egg to adult in a few weeks and then lay forty to sixty more eggs. They can destroy the whole harvest within months. Farmers can sell their crop immediately. (31) But selling at harvest time means more competition and lower prices. Or they can use poison to kill the bugs. But crop scientist Dieudonne Baributsa says that is also risky. "They end up misusing or overusing the poison. In Nigeria, they have reported a lot of cases of death. They usually call it in Nigeria ’killer beans’", says Dieudonne. Mr. Baributsa is a researcher at Purdue University in the American state of Indiana. Mr. Baributsa says the storage bags are thick enough that any insects already in the cowpeas will die from lack of oxygen. The lack of air will also help prevent the growth of bacteria that can ruin the harvest. (32) The bags cost about two dollars each. Mr. Baributsa says that is not much, especially if it means farmers can wait long enough to get a better price for their crop. The bags are produced locally. Donors currently support the project, but the groups involved are working to build a lasting market for the bags. Q: What is the purpose of using airtight plastic bags according to the passage [答案详解] 文章提到塑料保鲜袋有助于帮助农民在不用有害化学物质的情况下存放他们的收成以等待出售。故答案为D)。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>