名人教英文：待机耗能
家庭电器如电视、计算机和影音器材等，都有「备用」或「待机」状态，standby mode。待机状态的电器，其实仍在耗电；这耗用的电力叫standby power。经常让多件电器留在待机状态，会浪费大量standby power，增加碳排放，破坏环境。有环保组织提醒人们：household electronics can use up to 80 percent as much electricity on standby power as they do when they are turned on.
stand by是短语动词（phrasal verb），字面意思是「站在一旁」；例如the man was beaten to the ground as onlookers stood by. 那人被打至倒地，围观者站在一旁。从站在一旁，引伸为「候命」、「准备」等意思。例如飞机起飞时，机长会发出指示：cabin crew, please stand by for takeoff. 这当然不是叫机舱服务员在起飞时只管站在一旁，而是要大家作好起飞准备。
于是有解作「备用」的standby。作为名词，standby除了可如上述解作「备用状态」之外，还可用来指备用品、后备的人或物。例如︰when an operating unit fails, it is immediately replaced by a standby. 一个运行中的组件失灵，便立即由后备组件替换。又如：she is the standby for the lead role in this musical. 她是这出音乐剧主角的后备演员。这个名词的复数式是standbys：the standbys are regularly checked to ensure they are in good condition.
说个人或机构on standby，即准备候命，如hospitals are on standby ready to deal with casualties from the air crash. 医院已为治理空难伤者作好准备。the operation unit is on standby round the clock for emergency services. 行动小组24小时候命，提供紧急服务。
standby也可用作形容词，如后备发电机是standby generator，后备电池是standby battery，后备数据库是standby database。
短语动词stand by还有其他解法。如果你站在某人身旁，即是支持他的意思。she stood by her husband during his trial. 她的丈夫受审时，一直得到她的支持。一首很流行的歌，歌名stand by me，开头几句是︰when the night has come / and the land is dark / and the moon is the only light we'll see / no, i won't be afraid / oh, i won't be afraid / just as long as you stand, stand by me... 意思是只要你在我身旁（和我一起、支持我），我便不会害怕。
英语单词词汇学习：
standby power
待机状态下耗电
cabin crew
机舱服务员
round the clock
或round-the-clock