as and when used to refer to an uncertain future event.
2013Bit-Tech Gaming Murfy moves automatically as and when he's needed, but for him to perform an action requires the player to press a button.
英语词组固定搭配大全包含15956条英汉双解词组，基本涵盖了全部常用英文词组、短语的翻译及用法，是英语学习的有利工具。