基本解释自由项目英汉例句双语例句But the shift into travel spending, seen as a big-ticket discretionary item, is a sign perhaps of the next stage of the recovery.但旅游支出作为大额非必需品消费，可谓经济进一步恢复的信号。词组短语短语Non -Discretionary Item 必须支出项目专业释义计算机科学技术离散项目