=∑na4e(T)+RTLa]-∑ng4g(T)） =∑nsg(T)+RLx小-∑nag(I) =RT=RT∑nnL&<0 19 19 =  + − B B B B nB B (T) RTLnxB n (T) *    = RT=   0 B RT nB LnxB =  + − B B B B nB B (T) RTLnxB n (T)    