6.根据算式涂一涂，填一填。
$\frac{2}{3}×\frac{2}{3}=(\quad)$
$\frac{3}{5}×\frac{2}{3}=(\quad)$

$\frac{2}{3}×\frac{2}{3}=\frac{2×2}{3×3}=\frac{4}{9}$
$\frac{3}{5}×\frac{2}{3}=\frac{\overset{1}{\cancel{3}}×2}{5×\underset{1}{\cancel{3}}}=\frac{2}{5}$
$\frac{2}{3}×\frac{2}{3}=(\frac{4}{9})$
$\frac{3}{5}×\frac{2}{3}=(\frac{2}{5})$
涂法提示：第一个9格的长方形，先涂出全部的$\frac{2}{3}$（共6格），再将这6格中的$\frac{2}{3}$（共4格）用另一色叠涂；第二个15格的长方形，先涂出全部的$\frac{3}{5}$（共9格），再将这9格中的$\frac{2}{3}$（共6格）用另一色叠涂。

7.计算下面各题。
$\frac{2}{9}×18$
$39×\frac{2}{13}$
$\frac{2}{9}×\frac{3}{5}$
$\frac{5}{12}×\frac{7}{15}$
$\frac{9}{10}×\frac{5}{6}$
$\frac{3}{16}×\frac{4}{15}$
$\frac{7}{12}×\frac{3}{14}$
$\frac{8}{21}×\frac{7}{16}$
$\frac{13}{22}×\frac{11}{26}$
$\frac{9}{14}×\frac{7}{18}$
$\frac{16}{21}×\frac{7}{12}$
$\frac{7}{12}×\frac{8}{21}$

$\frac{2}{9}×18 = 4$
$39×\frac{2}{13} = 6$
$\frac{2}{9}×\frac{3}{5} = \frac{2}{15}$
$\frac{5}{12}×\frac{7}{15} = \frac{7}{36}$
$\frac{9}{10}×\frac{5}{6} = \frac{3}{4}$
$\frac{3}{16}×\frac{4}{15} = \frac{1}{20}$
$\frac{7}{12}×\frac{3}{14} = \frac{1}{8}$
$\frac{8}{21}×\frac{7}{16} = \frac{1}{6}$
$\frac{13}{22}×\frac{11}{26} = \frac{1}{4}$
$\frac{9}{14}×\frac{7}{18} = \frac{1}{4}$
$\frac{16}{21}×\frac{7}{12} = \frac{4}{9}$
$\frac{7}{12}×\frac{8}{21} = \frac{2}{9}$