铸管生产所用电炉的频率通常有三种：中频、变频和（）。
参考答案：工频
2004年A应纳个人所得税( )万元。
A．3.12
B．2.86
C．4.92
D．5.04
A government health study backs up the recommendation that one should be eating fruit and vegs in his diet.
