1. 直接写出得数。
实际用时：分钟
$\frac{3}{8}÷\frac{3}{7}=$ $\frac{5}{9}÷\frac{5}{18}=$ $\frac{7}{4}÷\frac{5}{7}=$ $\frac{1}{5}÷\frac{2}{3}=$
$\frac{5}{6}÷\frac{7}{8}=$ $\frac{7}{10}÷\frac{5}{6}=$ $\frac{16}{25}÷\frac{8}{9}=$ $\frac{13}{36}÷26=$
$\frac{5}{14}÷2=$ $15÷\frac{5}{7}=$ $\frac{5}{9}÷\frac{3}{4}=$ $\frac{4}{3}÷\frac{3}{4}=$
$\frac{1}{2}÷\frac{3}{11}=$ $\frac{5}{7}÷\frac{5}{6}=$ $\frac{1}{5}÷\frac{1}{4}=$ $\frac{9}{5}÷\frac{9}{5}=$
$\frac{9}{16}÷\frac{9}{8}=$ $\frac{6}{7}÷\frac{3}{14}=$ $\frac{12}{17}÷\frac{6}{7}=$ $\frac{7}{8}÷\frac{3}{4}=$
$\frac{1}{3}÷\frac{2}{3}=$ $\frac{8}{9}÷\frac{2}{7}=$ $\frac{2}{7}÷\frac{5}{7}=$ $\frac{5}{7}÷\frac{7}{5}=$

1. $\frac{7}{8}$ $2$ $\frac{49}{20}$ $\frac{3}{10}$
$\frac{20}{21}$ $\frac{21}{25}$ $\frac{18}{25}$ $\frac{1}{72}$
$\frac{5}{28}$ $21$ $\frac{20}{27}$ $\frac{16}{9}$
$\frac{11}{6}$ $\frac{6}{7}$ $\frac{4}{5}$ $1$
$\frac{1}{2}$ $4$ $\frac{14}{17}$ $\frac{7}{6}$
$\frac{1}{2}$ $\frac{28}{9}$ $\frac{2}{5}$ $\frac{25}{49}$

2. 计算下面各题。
$\frac{2}{7}+(\frac{5}{3}-\frac{2}{7})$
$\frac{5}{6}-(\frac{3}{4}-\frac{2}{5})$
$\frac{3}{5}-\frac{2}{7}+\frac{3}{5}$

2. $\frac{5}{3}$ $\frac{29}{60}$ $\frac{32}{35}$

3. 填一填。
(1) $4 ÷ $$ = \_\_\_\_\_\_$
(2) $6 ÷ $$ = \_\_\_\_\_\_$；$10 ÷ = \_\_\_\_\_\_$；$18 ÷ = \_\_\_\_\_\_$

3. (1) $8$ $16$ $32$
(2) $\frac{16}{5}$ $\frac{16}{3}$ $\frac{48}{5}$

已知$a⊙b=\frac{c}{a}+\frac{d}{b}$，若$\frac{1}{2}⊙\frac{1}{3}=13$，$\frac{1}{5}⊙\frac{1}{3}=19$，则$\frac{1}{4}⊙\frac{1}{7}$的值是多少？

【思维提升】29