when /wen/ I. adv.1. 什么时候，何时（疑问副词，引导疑问句；连结副词，引导名词从句和不定式短语）：When did you come here?你什么时候到这儿来的? When do you think it can be operated on? 你认为什么时间可以动手术? When she’ll be back depends much on the weather. 她什么时候回来要看天气而定。Ask him when to open it.请问他什么时间将它打开。 2. 在(哪个)时候 (=at which time) (关系副词，引起定语分句): He came at a time when I least expected him. 他在我意想不到的时候来了。［考句］It is human nature to think back to a Golden Age when one’s country was strong and respected.人的天性就是爱回想自己国家曾经繁荣昌盛的“黄金时代”。‖II. conj.1.当…的时候 (从属连词，可直接跟分词、形容词、名词或介词短语)：［考句］I was halfway back to the cottage where my mother lived when Susan caught up with me. 在我回母亲住宅的半路上，苏珊赶上了我。(When后既可接持续动词也可接瞬间动词，而while后只能接持续性动词) Phelps got engaged to her when travelling last winter. 去年冬天旅行时费尔普斯与她订了婚。If you lie upon roses when young, you’ll lie upon thorns when old.［谚］年轻时躺在玫瑰上，年老时就会躺在荆棘上(少年图安逸，老大徒伤悲)。When at Rome do as Romans do.［谚］入乡随俗。［考句］Michael used to look hurt and surprised when scolded.在受到责备时，迈克尔往往显得伤心和惊讶。2.那时(= and then，常可表示突然) (等立连词，前有逗号隔开): I was taking a walk, when I came across him. 我正在散步，碰见了他。［考句］I felt somewhat disappointed and was about to leave, when something occurred which attracted my attention. 我感到有些失望，正欲离开，这时突然发生了一件事吸引了我的注意。hardly… when 还没(刚刚)…就：I had hardly (=Hardly had I) gone to bed when the telephone rang. 我刚上床，电话铃就响了。just…when 刚…就：［考句］I had just started back for the house to change my clothes when I heard voices. 我刚动身回屋换衣服，就听到有人说话。‖III. pron. 什么时候； 某个时候：Until when can you stay? 你能住到什么时候? Since when I have been better. 从那时以后我就好了。
whenever /wenˈevə/ conj. 1.每当，每回，每次：I go to the theatre whenever I get the chance. 每当有机会我就去戏院看戏。 2.无论什么时候：You may leave whenever you please. 你想什么时候走就什么时候走。(cf. when ever…是对疑问词的强调，如：When ever will he start?他究竟什么时候动身?)
