2008又5/6+(-2009又3/4)-2010又1/2+2011又2/3
=(2008+5/6)-2009-3/4-2010-1/2+2011+2/3
=(2008-2009-2010+2011)+(5/6-3/4-1/2+2/3)
=0+1/4
=1/4