一般变压器最大效率出现在负载为额定容量的（）。
A、45％
B、50％
C、55％
D、60％
参考答案：D
Do you know _____ this time yesterday? [ ]
A. who are they waiting
B. who they are waiting for
C. who were they waiting
D. who they were waiting for
从法的本质上看，法最终决定于( )
A．社会物质生活条件
B．国家意志
C．掌握 * * 的阶级的意志
D．人类理性
