when

出处：按学科分类—语言、文字 辽宁人民出版社《英汉辞典》第1464页（813字）

【释义】：

ad．①(疑问副词)什么时候：When did you come to Shenyang?你什么时候到沈阳来的?When did you join the army?你什么时候参军的?②(连接副词，引导名词从句)什么时候：When the meeting is going to be held has not been decided yet．会什么时候开还没有定下来．Do you know when he was born?你知道他什么时候出生的吗?③(关系副词，引导定语从句)…的时候：I will never forget the day when I saw Chairman Mao．我将永远不会忘记见到毛主席的那一天．

－conj．①当…的时候，那时：It was raining when we arrived．当我们到达的时候，天正下雨．We skated till sunset，when it began to snow．我们滑冰一直滑到日落，那时天下起雪来．②虽然，既然：We have only three books when we need five．虽然我们需要五本书，但却只有三本．We had to put the meeting off when so many comrades were absent．既然很多人没来，会议只好延期．

－pron．什么时候，那时候：Till when will you wait?你能等到什么时候?Since when we have not written each other．从那时候起我们一直没有通信．

－n．(the when)时间．