原式=1/2 + 1/2乘3 + 1/3乘4 + 1/4乘5 + 1/5乘1/6
=1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6
=1-1/6
=5/6
绝对正确!
给点分!