1. 填空:
(1) $(-4) × 6 = \_\_\_\_\_\_$;
(2) $(-2) × (-0.5) = \_\_\_\_\_\_$;
(3) $(-\dfrac{3}{16}) × 4 = \_\_\_\_\_\_$;
(4) $\dfrac{2}{5} × (-\dfrac{3}{4}) = \_\_\_\_\_\_$.

1.(1)-24 (2)1 (3)$-\dfrac{3}{4}$ (4)$-\dfrac{3}{10}$

2. 计算:
(1) $-\dfrac{2}{3} × (-1.5)$;
(2) $(-3) × (-4) × (-\dfrac{4}{3})$;
(3) $(-2) × 3 × (+4) × (-1)$;
(4) $(-5) × (-5) × (-5) × 2$;
(5) $(-\dfrac{3}{7}) × (-\dfrac{4}{5}) × (-\dfrac{7}{12})$;
(6) $-\left|\dfrac{2}{7}\right| × (-28) × (-0.25) × (-1)$;
(7) $\dfrac{22}{7} × (-3.14) × |-3| × (-\dfrac{10}{3}) × 0 × \dfrac{355}{113}$;
(8) $(-8) × \dfrac{4}{3} × \dfrac{1}{10} × (-1.25) × (-\dfrac{5}{4})$;
(9) $(1-2) × (2-3) × (3-4) × ··· × (19-20)$.

2.(1)1 (2)-16 (3)24 (4)-250 (5)$-\dfrac{1}{5}$
(6)2 (7)0 (8)$-\dfrac{5}{3}$
(9)原式=$\underbrace{(-1)×\dots×(-1)}_{19个-1}=-1$.