2×4/1+4×6/1+6×8/1....+2006×2008/1=（1/2-1/4+1/4-1/6+1/6-1/8+……+1/2006-1/2008）÷2=（1/2-1/2008）÷2=1003/2008÷2=1003/4016
是啊
