一、口算。
$\frac{1}{7} ÷ \frac{5}{7} =$
$\frac{20}{21} ÷ \frac{14}{39} =$
$1 ÷ ( \frac{1}{2} + \frac{1}{3} ) =$
$\frac{2}{3} ÷ \frac{1}{3} =$
$10 ÷ \frac{5}{6} =$
$1 ÷ ( \frac{1}{3} + \frac{1}{4} ) =$
$\frac{2}{17} ÷ \frac{8}{17} =$
$\frac{10}{21} ÷ \frac{2}{7} =$
$1 ÷ ( \frac{1}{4} + \frac{1}{6} ) =$
$\frac{9}{10} ÷ \frac{3}{25} =$
$\frac{1}{2} ÷ \frac{3}{5} =$
$1 ÷ ( \frac{1}{6} + \frac{1}{8} ) =$
$\frac{1}{3} ÷ \frac{1}{4} =$
$\frac{5}{8} ÷ \frac{1}{16} =$
$1 ÷ ( \frac{1}{5} - \frac{1}{6} ) =$
$\frac{9}{10} ÷ \frac{5}{3} =$
$\frac{2}{13} ÷ \frac{1}{6} =$
$1 ÷ ( \frac{1}{4} + \frac{1}{12} ) =$
$\frac{1}{24} ÷ \frac{5}{8} =$
$\frac{3}{40} ÷ \frac{9}{10} =$
$1 ÷ ( \frac{1}{10} + \frac{1}{12} ) =$

1.$\frac{1}{5}$ 2.$\frac{130}{49}$ 3.$\frac{6}{5}$ 4.$2$ 5.$12$ 6.$\frac{12}{7}$ 7.$\frac{1}{4}$ 8.$\frac{5}{3}$ 9.$\frac{12}{5}$ 10.$\frac{15}{2}$ 11.$\frac{5}{6}$ 12.$\frac{24}{7}$ 13.$\frac{4}{3}$ 14.$10$ 15.$30$ 16.$\frac{27}{50}$ 17.$\frac{12}{13}$ 18.$3$ 19.$\frac{1}{15}$ 20.$\frac{1}{12}$ 21.$\frac{60}{11}$

二、计算下面各题，能用简便算法的就用简便算法。
$0.25 ÷ \frac{11}{6} ÷ \frac{1}{4}$
$\frac{1}{7} × \frac{9}{16} + \frac{5}{16} ÷ 7$
$( \frac{1}{6} + \frac{15}{24} ÷ \frac{3}{4} ) ÷ \frac{8}{5}$
$\frac{2}{3} + \frac{14}{9} ÷ \frac{7}{30}$
$\frac{5}{3} - \frac{5}{9} ÷ \frac{3}{2} - \frac{1}{6}$
$8 ÷ \frac{4}{5} + 2 ÷ \frac{4}{5}$

1.$\frac{6}{11}$ 2.$\frac{1}{8}$ 3.$\frac{5}{8}$ 4.$\frac{22}{3}$ 5.$\frac{61}{54}$ 6.$12\frac{1}{2}$