23.4

(1)(2)

1 PABCDABCDDAB60aPADABCD.

(1)GADBGPAD(2)ADPB.ABCDaPADABCD.

(1)PGPADGADPGAD.PADABCDPGABCDPGBG.ABCDDAB60ABDBGAD.ADPGGBGPAD.

(2)(1)BGADPGAD.ADPBGADPB.

1CDCDABCEEFFEC90EFDDCE.

CDCDABABCD.EFCDEF.FEC90EFEC.ECCDCEFDCE.EFEFDEFDDCE.

2 PABABCPACABCAEPBCE(1)PAABC(2)EPBCABC

(1)ABCDDFACFPACABCACDFPAC.PAPACDFPA.DGABGDGPA.DGDFDPAABC.

(2)BEPCH.EPBCPCBHAEPBCAEPCAEBEEPCABE.PCAB.PAABCPAABPAPCPABPACABACABC

(2)(1)

2abab..

PQaMNbQN.

aPQ.MN.PQMN.PQMNPQ.a.PQaPQaQ.

eq \o(,\s\up17(),\s\do15())eq \o(,\s\up17(),\s\do15())

3 PABCDPADABCDABCD2BAD60NPBADNPCMEAD

(1)ENPDC(2)BCPEB(3)PBCADMN.(1)ENDM.(2)ADPEBADBC(3)PBADMN.

(1)ADBCBCPBCADPBCADPBC.ADMNPBCMNADMN.BCADMNBC.NPBMPC

MNeq \f(1,2)BC.

EADMNDE.

DENM

ENDM.DMPDC.

ENPDC.

(2)ABCD2BAD60BEAD.PADEPEADADPBE.ADBCBCPEB.

(3)(2)ADPBE.PBPBEADPB.PAABNPBANPB.ANADAPBADMN.PBPBC.PBCADMN.

3PABCDABCDDAB60aPADABCD

(1)ADPB(2)EBCFDEFABCD

(1)GADPGPADPGAD.ABCDDAB60GADBGAD.BGPGGADPGB.PBPGBADPB.

(2)FPCDEFABCD.PCFDEEFDFPBCFEPB.ABCDGBDEFEDEFDEDEFEFDEE.DEFPGB.

(1)PGABCDPGPGBPGBABCDDEFABCD.