变压器的效率是变压器的（）的百分比。
A、输出有功功率与输入有功功率
B、输入有功功率与输出有功功率
C、铁损耗与铜损耗
D、铜损耗与铁损耗
参考答案：A
---- My brother is not good at speaking English.
---- I suggest English for two hours every day.
A．he practice speaking
B．him to speak
C．he speaking
D．his practicing to speak
请说明N型、D型、R型酸性冷烫液各适合于何种头发或发式？
