2. 想一想,填一填。
$\frac{1}{4}÷\frac{3}{4}= \frac{1}{4}×$()= ()
$\frac{3}{8}÷\frac{1}{5}= \frac{3}{8}×$()= ()
$\frac{4}{5}÷4= \frac{4}{5}×$()= ()
$4÷\frac{3}{4}= 4×$()= ()
$\frac{9}{16}÷\frac{3}{4}= \frac{9}{16}×$()= ()

$\frac{1}{4}÷\frac{3}{4}= \frac{1}{4}×\frac{4}{3}= \frac{1}{3}$
$\frac{3}{8}÷\frac{1}{5}= \frac{3}{8}×5= \frac{15}{8}$
$\frac{4}{5}÷4= \frac{4}{5}×\frac{1}{4}= \frac{1}{5}$
$4÷\frac{3}{4}= 4×\frac{4}{3}= \frac{16}{3}$
$\frac{9}{16}÷\frac{3}{4}= \frac{9}{16}×\frac{4}{3}= \frac{3}{4}$

3. 看谁做得又对又快。
$8÷\frac{6}{7}$ $\frac{1}{2}÷\frac{2}{5}$ $35÷\frac{5}{14}$
$\frac{3}{4}÷\frac{3}{8}$ $25×\frac{1}{5}$ $\frac{1}{5}×\frac{8}{9}$

$=8×\frac 76$
$ =\frac {28}3$
$=\frac 12×\frac 52$
$ =\frac 54$
$=35×\frac {14}5$
=98
$=\frac 34×\frac 83$
=2
$=\frac {25}5$
=5
$=\frac {1×8}{5×9}$
$ =\frac 8{45}$