基本解释自由項目英汉例句雙語例句But the shift into travel spending, seen as a big-ticket discretionary item, is a sign perhaps of the next stage of the recovery.但旅遊支出作爲大額非必需品消費，可謂經濟進一步恢複的信號。discretionary item更多例句词组短语短語Non -Discretionary Item 必須支出項目discretionary item更多词组专业释义計算機科學技術離散項目