29【除草剂】 by CCaCC 有一个是除草剂对玉米有效，对棉花无效，这种效果超过一年以上。 问农民不愿使用除草剂的原因？选因为两种作物交替使用。
【GWD】GWD-TN-21 17题 It is crucially important to farmers that the herbicides they use to control weeds not damage their crops. One very effective herbicide is safe for corn, but soybeans are damaged even by the herbicide’s residue, which remains in the soil more than a year after the herbicide is applied. Soybeans and corn are not sown together in the same filed; nevertheless, most farmers are reluctant to use the herbicide on their corn. Which of the following, if true, provides the strongest justification for the farmers’ reluctance?
A. The residue of the herbicide in the soil a year after application is not enough to control most weeds effectively. B. To maintain the nutrients in the soil, corn and soybeans are often planted in a field in alternate years. C. The demand for soybeans is growing faster than is the demand for corn. D. For maximum yield, soybean plants are grown closer together to each other than are corn plants. E. The application of herbicides is less critical for soybean than for corn crops.