$ \frac {1}{3}=\frac {2}{6}=\frac {3}{9}=\frac {4}{12}=\frac {5}{15}=\frac {6}{18}=\frac {7}{21}=\frac {8}{24}$
$ \frac {1}{8}=\frac {2}{16}=\frac {3}{24}$
$ \frac {1}{6}=\frac {2}{12}=\frac {3}{18}=\frac {4}{24}$
$ $因为$\frac {8}{24}>\frac {4}{24}>\frac {3}{24},$
所以$\frac {1}{3}>\frac {1}{6}>\frac {1}{8}$