三相星接负载在有中线情况下其单相负载端电压（）。
A、恒等于相电压
B、恒等于线电压
C、有时等于相电压
D、有时等于线电压
参考答案：A
—Are these his cousins?
—_______. They are his brothers.[ ]
A. Yes, they are.
B. No, these aren’t.
C. Yes, these are.
D. No, they aren’t.
铸件的最小允许壁厚和铸造合金的（）密切相关。
A.力学性能
B.流动性
C.熔点
D.凝固特性
