电能质量的指标是（）
A、电流和电压
B、有功和无功
C、频率和电压
D、电流和频率
参考答案：C
Good teachers can usually give the students______ advice on their study.
A．a great many
B．huge amounts of
C．a large number of
D．too many
下列程序的执行结果是 public class Testhh public static void main(String args [] ) Strings1=new String("I am boy")； Strings2=new String("I am boy")； System.out.println(s1.equals(s2))；
A．true
B．false
C．I am boy
D．都不正确
