"sCholArly skywriting" hAs All thE Following ADvAntAgEs ExCEpt _________.
A．AvoiDAnCE oF Copyright trouBlE
B．swiFt trAnsmission oF thought
C．utilizAtion oF thE wisDom oF othEr inDiviDuAls
D．EAsy upDAting oF mAnusCripts