ƚ  0V Q .   &  & MathType0Times New Roman؟ww w f-2  0y2 5y2 9y2 :2y Times New Roman؟ww w f-2 2ySymbol ؟ww w f-2 =y2 -y2 -yTimes New Roman؟ww w f-2 xy2 xy & "System f !-