“when” 和 “while” 都可以表示“当……时”,但它们在用法上有一些区别:
1. 时间关系不同
when:可以表示某个时间点或时间段,动作可以是瞬间的或持续的。
When I arrived, she was cooking.(当我到达时,她在做饭。→ “到达”是瞬间动作)
When I was young, I loved ice cream.(我小时候很喜欢冰淇淋。→ “小时候”是时间段)
while:通常表示两个动作同时发生,且强调持续性的动作或状态。
While I was cooking, she watched TV.(我在做饭时,她在看电视。→ 两个动作同时持续)
He fell asleep while reading.(他看书时睡着了。→ “看书”是持续动作)
2. 从句动词形式不同
when:从句可以用瞬间动词或持续动词。
When the phone rang, I was sleeping.(电话响时,我在睡觉。→ “rang”是瞬间动词)
When I lived in Beijing, I visited the Great Wall.(我住北京时去过长城。→ “lived”是持续动词)
while:从句通常用持续动词(如进行时或状态动词)。
While I was walking, it started to rain.(我走路时,开始下雨了。→ “was walking”是进行时)
While she studies, she listens to music.(她学习时会听音乐。→ “studies”是持续动作)
3. 特殊用法
when 可以表示“突然发生某事”(常用于过去时):
I was about to leave when the phone rang.(我正要离开,突然电话响了。)
while 可以表示对比(类似“而”):
She likes coffee, while I prefer tea.(她喜欢咖啡,而我更喜欢茶。)