第25题: [单项选择]A new technique ______ , the yields as a whole increased by 20 percent. A. working out B. having worked out C. having been worked out D. to have been worked out 参考答案:C 答案解析:[解析] 由于开发了新技术,总产量增加了20%。 [解析] 考查独立结构。根据句子结构,这里应该用独立分词结构,故选项D错误。同时,work out和a new technique是逻辑