PP P (a)U/(2P2)=U(P)+U(P2) (d)U(2P)=2U(P (b) p(e) P (b)U(B2,P2)=U(R)+U(2),(e)U(P,M)=U(P)+U/(M) C M (c)U(M12M2)=U(M1+U(M2)P1 (a) P2 P1 P2 (b) P P (d) P M (e) ( ) ( , ) ( ) ( ); a U P1 P2 =U P1 +U P2 ( ) ( , ) ( ) ( ); b U P1 P2 =U P1 +U P2 ( ) ( , ) ( ) ( ); U M1 M2 U M1 U M2 c = + (d) U(2P) = 2U(P); (e) U(P,M) =U(P) +U(M) M1 M2 (c)