6. 计算:
(1) $-2^3 + 4 × (-3)^2$;
(2) $-2^3 ÷ ( -2 - \frac{1}{4} ) × ( -\frac{1}{3} )$;
(3) $( \frac{2}{3} )^3 ÷ \frac{2^3}{3} - (-3)^2 + (-3^2)$;
(4) $-2^4 × [ \frac{1}{2} - ( -\frac{1}{2} )^2 + 3 ÷ (-8) ]$.

(1) 解:原式 = 28.
(2) 解:原式 = $-\dfrac{32}{27}$.
(3) 解:原式 = $-17\dfrac{8}{9}$.
(4) 解:原式 = 2.