-1/2a^2b-[3\2a^2b-3(abc-1\3a^2c)-4a^2c]-3abc
=-1/2a^2b-3\2a^2b+3abc-a^2c+4a^2c-3abc
=-2a^2b+3a^2c
=-2×1×1+3×1×（-1/3）
=-2-1
=-3