一、口算。
$\frac{7}{12}×\frac{4}{7}=$
$4.5×\frac{7}{18}=$
$\frac{5}{24}×6=$
$\frac{5}{12}×\frac{2}{7}=$
$\frac{4}{5}×\frac{5}{6}=$
$\frac{25}{14}×\frac{28}{5}=$
$\frac{5}{7}×\frac{7}{9}=$
$\frac{16}{27}×\frac{9}{64}=$
$1.5×\frac{4}{5}=$
$\frac{3}{10}×\frac{9}{5}=$
$\frac{3}{23}×0.46=$
$\frac{9}{5}×\frac{1}{2}=$
$\frac{3}{7}×2.1=$
$\frac{6}{7}×\frac{2}{3}=$
$21×\frac{5}{7}=$
$\frac{17}{4}×0.8=$
$\frac{1}{12}×60=$
$\frac{5}{4}×0.36=$
$\frac{5}{78}×3.9=$
$\frac{1}{24}×0.6=$
$\frac{4}{25}×\frac{125}{48}=$

1.$\frac{1}{3}$ 2.$\frac{7}{4}$ 3.$\frac{5}{4}$ 4.$\frac{5}{42}$ 5.$\frac{2}{3}$ 6.$10$ 7.$\frac{5}{9}$ 8.$\frac{1}{12}$ 9.$1.2$ 10.$\frac{27}{50}$ 11.$0.06$ 12.$\frac{9}{10}$ 13.$3$ 14.$\frac{4}{7}$ 15.$15$ 16.$3.4$ 17.$5$ 18.$0.45$ 19.$\frac{1}{4}$ 20.$\frac{1}{40}$ 21.$\frac{5}{12}$

二、计算下面各题。
$\frac{5}{8} - (\frac{1}{2} + \frac{3}{5}) × \frac{5}{11}$
$\frac{4}{5} × (\frac{5}{6} + \frac{3}{4}) + \frac{4}{5}$
$\frac{2}{3} + (\frac{4}{5} - \frac{2}{3}) × \frac{5}{3}$
$(15 - 14 × \frac{4}{7}) × \frac{8}{21}$
$\frac{5}{8} - \frac{1}{3} × (\frac{5}{8} - \frac{1}{2})$
$(\frac{7}{9} - \frac{2}{3}) × \frac{9}{10} × \frac{1}{12}$

1.$\frac{1}{8}$ 2.$\frac{31}{15}$ 3.$\frac{8}{9}$ 4.$\frac{8}{3}$ 5.$\frac{7}{12}$ 6.$\frac{1}{120}$