2乘1又1/2乘1又1/3乘...乘1又1/2006乘1又1/2007
= 2×(3/2)×(4/3)×...×(2007/2006)×(2008/2007)
= (2×3×4×...×2007×2008)/(2×3×4×...×2006×2007)
= 2008