=2002/(2002+2002/2003)+1/2004
=2002/2002+2002/(2002/2003)+1/2004
=1+2003+1/2004
=2004又2004分之1
2002÷2002又2003分之2002+2004分之1
=2002/(2002+2002/2003)+1/2004
=2002/2002+2002/(2002/2003)+1/2004
=1+2003+1/2004
=2004又2004分之1