thE mAin DiFFErEnCE BEtwEEn gnutEllA AnD nApstEr is thAt_________.
A．noBoDy CAn BloCk nApstEr's sEArChing
B．thEir sEArChEs ArE ConDuCtED DiFFErEntly
C．it is muCh morE DiFFiCult to givE AwAy nApstEr
D．gnutEllA nEEDs A CEntrAl sErvEr ComputEr to sEArCh