In the main post , I said
I meant emitter is not connected to GND.
Yes, for the transistor to trun on Vbe = 0.6.
In common emitter mode, emitter is directly connected to ground, so by by giving a base valtage of 06-0.7V , one can turn on the transistor(Vbe= 0.6-0.7),
but in common collector...