三相四线电能表无功功率表达式为（ ）。
AP=UAIAcosφA+UBIBcosφB+UCICcosφC
BP=UAIAsinφA+UBIBsinφB+UCICsinφC
CP=UAIAtgφA+UBIBctgφB+UCICctgφC
DP=3UIctgφA
AP=UAIAcosφA+UBIBcosφB+UCICcosφC
BP=UAIAsinφA+UBIBsinφB+UCICsinφC
CP=UAIAtgφA+UBIBctgφB+UCICctgφC
DP=3UIctgφA