计算:(每小题3分,共12分)(1)-4-5+7 (2)8×(-1)2-(-4)+(-3) (3)(-2)3÷-(-5)× (4)5(x-3 y) - (-2 y+x )
计算:-(-2)2+()0.
计算:
计算:()-1+(π-1)0+27.