一、口算。
$\frac {7}{9}×\frac {9}{28}=$
$\frac {25}{48}×\frac {4}{5}=$
$\frac {3}{5}×\frac {5}{9}=$
$\frac {5}{28}×\frac {7}{45}=$
$\frac {3}{8}×\frac {4}{9}=$
$\frac {7}{24}×\frac {3}{14}=$
$\frac {5}{6}×\frac {1}{10}=$
$\frac {5}{6}×\frac {3}{4}=$
$\frac {11}{15}×\frac {25}{33}=$
$\frac {3}{4}×\frac {6}{5}=$
$\frac {3}{11}×\frac {22}{9}=$
$\frac {5}{12}×\frac {2}{3}=$
$\frac {3}{4}×\frac {8}{9}=$
$\frac {4}{9}×\frac {6}{7}=$
$\frac {7}{8}×\frac {5}{14}=$
$\frac {4}{13}×\frac {3}{8}=$
$\frac {25}{121}×\frac {11}{50}=$
$\frac {8}{15}×\frac {25}{24}=$
$\frac {4}{5}×\frac {5}{16}=$
$\frac {7}{12}×\frac {4}{7}=$
$\frac {5}{7}×0.4=$

$\frac{1}{4}$ $\frac{5}{12}$ $\frac{1}{3}$ $\frac{1}{36}$ $\frac{1}{6}$ $\frac{1}{16}$ $\frac{1}{12}$ $\frac{5}{8}$ $\frac{5}{9}$ $\frac{9}{10}$ $\frac{2}{3}$ $\frac{5}{18}$ $\frac{2}{3}$ $\frac{8}{21}$ $\frac{5}{16}$ $\frac{3}{26}$ $\frac{1}{22}$ $\frac{5}{9}$ $\frac{1}{4}$ $\frac{1}{3}$ $\frac{2}{7}$

二、根据算式涂一涂、画一画,再计算。


$\frac {1}{3}×\frac {1}{4}= \frac {( )}{( )}$


$\frac {3}{4}×\frac {2}{3}= \frac {( )}{( )}$
$\frac {3}{4}×\frac {2}{5}= \frac {( )}{( )}$
$\frac {2}{3}×\frac {4}{5}= \frac {( )}{( )}$

$\frac{1}{12}$ $\frac{1}{2}$ $\frac{3}{10}$ $\frac{8}{15}$

$\frac{1}{3}×\frac{1}{4}=\frac{1×1}{3×4}=\frac{1}{12}$
$\frac{3}{4}×\frac{2}{3}=\frac{3×2}{4×3}=\frac{6}{12}=\frac{1}{2}$
$\frac{3}{4}×\frac{2}{5}=\frac{3×2}{4×5}=\frac{6}{20}=\frac{3}{10}$
$\frac{2}{3}×\frac{4}{5}=\frac{2×4}{3×5}=\frac{8}{15}$