一、口算。
$\frac{1}{3}-\frac{1}{3}=$ $\frac{2}{4}+\frac{1}{4}=$ $\frac{3}{10}+\frac{4}{10}=$
$\frac{4}{9}+\frac{3}{9}=$ $\frac{5}{5}-\frac{4}{5}=$ $\frac{4}{7}-\frac{3}{7}=$
$\frac{2}{10}+\frac{3}{10}=$ $\frac{8}{9}-\frac{4}{9}=$ $\frac{6}{8}+\frac{1}{8}=$
$\frac{6}{7}-\frac{5}{7}=$ $\frac{2}{3}-\frac{2}{3}=$ $\frac{8}{8}-\frac{6}{8}=$
$\frac{7}{10}+\frac{1}{10}=$ $\frac{6}{9}+\frac{2}{9}=$ $\frac{5}{8}+\frac{2}{8}=$
$\frac{2}{5}-\frac{2}{5}=$ $\frac{5}{7}-\frac{2}{7}=$ $\frac{2}{9}+\frac{1}{9}=$
$\frac{4}{6}-\frac{1}{6}=$ $\frac{2}{9}+\frac{5}{9}=$ $\frac{9}{10}-\frac{1}{10}=$
$\frac{8}{10}-\frac{5}{10}=$ $\frac{3}{10}-\frac{2}{10}=$ $\frac{2}{5}+\frac{1}{5}=$
$\frac{8}{9}-\frac{5}{9}=$ $\frac{2}{4}-\frac{1}{4}=$ $\frac{4}{8}+\frac{2}{8}=$
$\frac{4}{7}-\frac{4}{7}=$ $\frac{2}{6}+\frac{2}{6}=$ $\frac{7}{9}+\frac{1}{9}=$
$\frac{5}{8}-\frac{3}{8}=$ $\frac{1}{6}+\frac{1}{6}=$ $\frac{6}{7}-\frac{4}{7}=$
$\frac{1}{10}+\frac{5}{10}=$ $\frac{6}{8}-\frac{4}{8}=$ $\frac{1}{8}+\frac{4}{8}=$

一、0 $\dfrac{3}{4}$ $\dfrac{7}{10}$
$\dfrac{7}{9}$ $\dfrac{1}{5}$ $\dfrac{1}{7}$
$\dfrac{5}{10}$ $\dfrac{4}{9}$ $\dfrac{7}{8}$
$\dfrac{1}{7}$ 0 $\dfrac{2}{8}$
$\dfrac{8}{10}$ $\dfrac{8}{9}$ $\dfrac{7}{8}$
0 $\dfrac{3}{7}$ $\dfrac{3}{9}$
$\dfrac{3}{6}$ $\dfrac{7}{9}$ $\dfrac{8}{10}$
$\dfrac{3}{10}$ $\dfrac{1}{10}$ $\dfrac{3}{5}$
$\dfrac{3}{9}$ $\dfrac{1}{4}$ $\dfrac{6}{8}$
0 $\dfrac{4}{6}$ $\dfrac{8}{9}$
$\dfrac{2}{8}$ $\dfrac{2}{6}$ $\dfrac{2}{7}$
$\dfrac{6}{10}$ $\dfrac{2}{8}$ $\dfrac{5}{8}$