单相变压器U1N /U2N=220/110V,一次侧加220V时,空载电流为1A;今将一次、二次侧绕组顺极性串联,外施330V电压,则空载电流为 。 ( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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