when: adv.1.〔疑问〕什么时候，几时。 W- did you see him (这以前)你几时见他的？2.〔关系，引导定语从句〕当…的时候。 He came at a time when I least expected him. 他在我最想不到的时候来了。3.从前境况差时。brag of having known sb. when 夸耀自己是某人过去的患难之交[布衣之交]。
When instructed to do so , turn off your device when on board an aircraft . any use of a device must be in accordance with applicable regulations per airline crew instructions 在飞机上在登机后，请按要求关闭您的电子设备。任何电子设备的使用均需符合机舱机组人员规定。
