单选题 Recent studies have indicated that a performance-based pay system is ______ more effective than other systems for achieving business goals.
  • A. significance
  • B. significant
  • C. signify
  • D. significantly
【正确答案】 D
【答案解析】[解析] 单词形态：副词 1．选项均为动词signify的不同形式。 2．空格内须填入一个副词来修饰后面的形容词比较级。因此D significantly为正确选项。