Darming主动跟Lingling打招呼叫说: .
_____ all the inventions have in common is ______ they have succeeded.
(I)若曲线y= f(x)在点(1, f(1) )处的切线与X轴平行,求a:
(II)若 f(x) 在x=2处取得极小值,求a的取值范围。