什么是电气设备的主保护和后备保护?
主保护就是能够快速而且有选择地切除被保护区域内故障的保护。后备保护就是当某一元件的主保护或断路器拒绝动作时,能够以较长的时限切除故障的保护
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____beforewedepartthedayaftertomorrow,weshouldhaveawonderfuldinnerparty.
Withonelegbrokeninthatcaraccident,hecannotevenwalk,____run.
Her____washeldatthelocalchurch.
Hereisapieceofpaper_____(在上面写着那本书的标题)TheArabianNights.
Whoistheman____(你刚才在操场和他握手)?