对于三相对称交流电路,不论星形或三角形接法,下列结论正确的有()。
A、P=3UmImcosφABCD
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Wehavebeenimportingandexportingallkindsofmetalsandmineralsfor30yearsandhavemanycustomersandfriendsinover80countriesandregions.
StudentswanttokeeptheSelf-AccessCentrebecause____.
竞争激烈的运动项目不适合年纪特别小的孩子。
Paymentofthepurchaseistobeeffectedbyanirrevocableletterofcreditinourfavour,payablebydraftatsightinpoundssterlinginLondon.