一、在$◯$里填上适当的运算符号。
$\frac{1}{8}◯\frac{5}{8}=\frac{3}{4}$
$\frac{7}{9}◯\frac{1}{3}=\frac{4}{9}$
$\frac{3}{4}◯\frac{1}{4}=\frac{1}{2}$
$\frac{5}{12}◯\frac{1}{4}=\frac{1}{6}$
$\frac{7}{18}◯\frac{1}{6}=\frac{5}{9}$
$1-\frac{3}{8}-\frac{5}{8}=1-(\frac{3}{8}◯\frac{5}{8})$

$\frac{1}{8}\boldsymbol{+}\frac{5}{8}=\frac{3}{4}$
$\frac{7}{9}\boldsymbol{-}\frac{1}{3}=\frac{4}{9}$
$\frac{3}{4}\boldsymbol{-}\frac{1}{4}=\frac{1}{2}$
$\frac{5}{12}\boldsymbol{-}\frac{1}{4}=\frac{1}{6}$
$\frac{7}{18}\boldsymbol{+}\frac{1}{6}=\frac{5}{9}$
$1-\frac{3}{8}-\frac{5}{8}=1-(\frac{3}{8}\boldsymbol{+}\frac{5}{8})$

二、蝴蝶落到哪朵花上？（比较大小）
＞ ＜ =
0.36 $\frac{9}{25}$
4.75 $4\frac{5}{7}$
$\frac{3}{8}$ 0.25
1.99 $1\frac{9}{10}$
2.33 $\frac{7}{3}$
$3\frac{1}{2}$ 3.2

$0.36 = \frac{9}{25}$
$4.75 ＞ 4\frac{5}{7}$
$\frac{3}{8} ＞ 0.25$
$1.99 ＞ 1\frac{9}{10}$
$2.33 ＜ \frac{7}{3}$
$3\frac{1}{2} ＞ 3.2$

三、计算题。（能简便计算的要简便计算）

$2 - \frac{7}{5} + \frac{2}{5}$
$\frac{1}{7} + \frac{1}{4} + \frac{6}{7}$
$\frac{1}{15} + ( \frac{1}{5} - \frac{1}{6} )$
$\frac{29}{23} - \frac{3}{8} - \frac{5}{8}$
$\frac{25}{28} - ( \frac{3}{7} + \frac{5}{14} )$
$\frac{3}{4} + \frac{5}{6} - \frac{1}{6}$

$2 - \frac{7}{5} + \frac{2}{5}$
$= 2 - (\frac{7}{5} - \frac{2}{5})$
$= 2 - 1$
$= 1$
$\frac{1}{7} + \frac{1}{4} + \frac{6}{7}$
$= (\frac{1}{7} + \frac{6}{7}) + \frac{1}{4}$
$= 1 + \frac{1}{4}$
$= 1\frac{1}{4}$
$\frac{1}{15} + ( \frac{1}{5} - \frac{1}{6} )$
$= \frac{1}{15} + \frac{3}{15} - \frac{1}{6}$
$= \frac{4}{15} - \frac{1}{6}$
$= \frac{8}{30} - \frac{5}{30}$
$= \frac{1}{10}$
$\frac{29}{23} - \frac{3}{8} - \frac{5}{8}$
$= \frac{29}{23} - ( \frac{3}{8} + \frac{5}{8} )$
$= \frac{29}{23} - 1$
$= \frac{6}{23}$
$\frac{25}{28} - ( \frac{3}{7} + \frac{5}{14} )$
$= \frac{25}{28} - ( \frac{12}{28} + \frac{10}{28} )$
$= \frac{25}{28} - \frac{22}{28}$
$= \frac{3}{28}$
$\frac{3}{4} + \frac{5}{6} - \frac{1}{6}$
$= \frac{3}{4} + ( \frac{5}{6} - \frac{1}{6} )$
$= \frac{3}{4} + \frac{2}{3}$
$= \frac{9}{12} + \frac{8}{12}$
$= \frac{17}{12}$