2007/2008×2009
=2007/2008×（2008+1）
=2007/2008×2008+2007/2008×1
=2007+2007/2008
=2007又2007/20082008×2006/2009
=（2009-1）×2006/2009
=2009×2006/2009-1×2006/2009
=2006-2006/2009
=2005又3/20092006-2006/2009怎么等于2005又3/20092006=2005+2009/20092006=2005+2009/20092005+2009/2009-2006/2009
=2005+3/2009
=2005又3/2009懂不嗯