dc指数法实质上是（）。
参考答案：机械钻速法
我国历史上首创封建成文法典总则篇的法典是( )。
A．《刑书》
B．《秦律》
C．《法经》
D．《汉律》
—John’s English is very good.
—Yes. I want to know ______. [ ]
A.when he started to learn English.
B.when did he start to learn English
C.how long did he learn English
D.how long he learn English
