变压器型号SF2-6300/220的含义是()。
A、三相、风冷;
B、额定容量为6300KVA;
C、高压绕组额定电压220KV;
D、有载调压。
参考答案:A, B, C
Yesterday he called ____me ____my office and told me the good news.[ ]
A. at, at
B. on, on
C. at, on
D. on ,at