whAt wAs thE holmEs' iDEA ABout knowlEDgE-lEArning
A．lEArning whAt EvEry BoDy lEArnED.
B．lEArning whAt wAs usEFul to you.
C．lEArning whAtEvEr you CAmE ACross.
D．lEArning whAt wAs DiFFErEnt to you.