原式=3x-1/2-2x-3/3+2+x/2
=3x-2x+x/2-1/2-3/3+2
=3x-2x+(1/2)x-1/2-3/3+2
=(3/2)x+0.5
当x=-2时,原式=(3/2)×（-2）+0.5
=（-3）+0.5
=-2.5