1. 计算。
$\frac{7}{10} × \frac{5}{7} + \frac{1}{2} =$ $1 - \frac{5}{8} ÷ 5 × \frac{8}{9} =$
$\frac{5}{8} ÷ \frac{5}{7} - \frac{1}{8} =$ $9 ÷ 15 - \frac{9}{30} × 2 =$
$6 ÷ 7 - \frac{1}{7} × 4 =$ $\frac{5}{8} + \frac{3}{4} ÷ \frac{2}{3} × \frac{1}{9} =$

1
$​\frac {8}{9}​$
$​\frac {3}{4}​$
0
$​\frac {2}{7}​$
$​\frac {3}{4}​$

2. 计算。
$(\frac{3}{4} - \frac{1}{2}) ÷ (\frac{1}{6} + \frac{2}{5})$ $\frac{5}{9} + [\frac{2}{3} ÷ (1 - \frac{1}{6})]$
$3 ÷ \frac{3}{5} - \frac{3}{5} ÷ 3$ $4 - [(\frac{1}{3} + \frac{5}{6}) × \frac{3}{7}]$

$​=\frac {1}{4}÷\frac {17}{30}​$
$​=\frac {15}{34}​$
$​=\frac {5}{9}+(\frac {2}{3}÷\frac {5}{6})​$
$​=\frac {5}{9}+\frac {4}{5}​$
$​=\frac {61}{45}​$
$​=5-\frac {1}{5}​$
$​=4\frac 45​$
$​=4-\frac {1}{2}​$
$​=3\frac 12​$

3. 添上四则运算符号或括号，使下列等式成立。
$1$ $\frac{1}{2}$ $\frac{1}{3}$ $\frac{1}{6}$ $= 0$ $1$ $\frac{1}{2}$ $\frac{1}{3}$ $\frac{1}{6}$ $= 1$
$1$ $\frac{1}{2}$ $\frac{1}{3}$ $\frac{1}{6}$ $= 2$ $1$ $\frac{1}{2}$ $\frac{1}{3}$ $\frac{1}{6}$ $= 3$
$1$ $\frac{1}{2}$ $\frac{1}{3}$ $\frac{1}{6}$ $= 4$ $1$ $\frac{1}{2}$ $\frac{1}{3}$ $\frac{1}{6}$ $= 5$