试题题干
Translate the following sentence into Chinese.
A United States Agricultural Department survey states that erosion continues at its present rate, corn and soybean yields in the Midwest may drop as much as 30 percent over the next 50 years.
参考答案
试题解析
考点：erosion 侵蚀；corn and soybean 玉米和大豆；yields 产量。
句子结构：句子主干为A United States Agricultural Department survey states，that引导宾语从句，从句主干为corn and soybean yields may drop as much as 30 percent。