一、口算。
$\frac {4}{5}÷\frac {1}{2}=$ $\frac {3}{4}×36=$ $\frac {8}{9}÷4=$
$\frac {2}{3}÷\frac {2}{3}=$ $\frac {1}{4}÷\frac {1}{3}=$ $\frac {5}{6}×\frac {2}{5}=$
$\frac {1}{2}÷\frac {2}{5}=$ $\frac {2}{5}+\frac {7}{10}=$ $\frac {5}{6}-\frac {5}{8}=$
$\frac {5}{9}×18=$ $\frac {6}{7}÷\frac {3}{5}=$ $24÷\frac {2}{3}=$
$\frac {5}{12}÷\frac {15}{4}=$ $\frac {6}{7}×\frac {21}{32}=$ $\frac {3}{5}-\frac {1}{2}=$
$\frac {1}{7}÷\frac {1}{2}=$ $4÷\frac {8}{11}=$ $\frac {1}{4}+\frac {9}{14}=$
$\frac {3}{8}×\frac {4}{5}=$ $\frac {2}{3}+\frac {2}{3}=$ $\frac {3}{7}÷\frac {3}{4}=$

一、$\frac{8}{5}$ 27 $\frac{2}{9}$ 1 $\frac{3}{4}$ $\frac{1}{3}$ $\frac{5}{4}$ $\frac{11}{10}$ $\frac{5}{24}$ 10 $\frac{10}{7}$ 36 $\frac{1}{9}$ $\frac{9}{16}$ $\frac{1}{10}$ $\frac{2}{7}$ $\frac{11}{2}$ $\frac{25}{28}$ $\frac{3}{10}$ $\frac{4}{3}$ $\frac{4}{7}$

二、计算下面各题。
$\frac {8}{17}÷\frac {4}{5}÷\frac {5}{34}$ $\frac {5}{21}÷\frac {4}{7}×\frac {3}{10}$ $\frac {5}{8}÷10÷\frac {5}{12}$
$\frac {1}{28}×\frac {7}{9}÷\frac {5}{6}$ $48×\frac {7}{18}÷\frac {2}{3}$ $\frac {2}{15}÷\frac {3}{14}÷8$

二、4 $\frac{1}{8}$ $\frac{3}{20}$ $\frac{1}{30}$ 28 $\frac{7}{90}$

$\frac{8}{17}÷\frac{4}{5}÷\frac{5}{34}$
$=\frac{8}{17}×\frac{5}{4}×\frac{34}{5}$
$=\frac{10}{17}×\frac{34}{5}$
$=4$
$\frac{5}{21}÷\frac{4}{7}×\frac{3}{10}$
$=\frac{5}{21}×\frac{7}{4}×\frac{3}{10}$
$=\frac{5}{12}×\frac{3}{10}$
$=\frac{1}{8}$
$\frac{5}{8}÷10÷\frac{5}{12}$
$=\frac{5}{8}×\frac{1}{10}×\frac{12}{5}$
$=\frac{1}{16}×\frac{12}{5}$
$=\frac{3}{20}$
$\frac{1}{28}×\frac{7}{9}÷\frac{5}{6}$
$=\frac{1}{36}×\frac{6}{5}$
$=\frac{1}{30}$
$48×\frac{7}{18}÷\frac{2}{3}$
$=\frac{56}{3}×\frac{3}{2}$
$=28$
$\frac{2}{15}÷\frac{3}{14}÷8$
$=\frac{2}{15}×\frac{14}{3}×\frac{1}{8}$
$=\frac{28}{45}×\frac{1}{8}$
$=\frac{7}{90}$