1 填一填。
(1)$\dfrac{3}{7}$里面有( )个$\dfrac{1}{7}$,再加上( )个$\dfrac{1}{7}$,就是$1$；$1$里面有( )个$\dfrac{1}{10}$。
(2)$\dfrac{2}{8}+\dfrac{3}{8}= $( ),( )个$\dfrac{1}{8}$加( )个$\dfrac{1}{8}$是( )个$\dfrac{1}{8}$,就是$\dfrac{( )}{( )}$。
(3)$1-\dfrac{2}{6}= $( ),( )个$\dfrac{1}{6}$减( )个$\dfrac{1}{6}$是( )个( ),就是$\dfrac{( )}{( )}$。
(4)
这些桃子的$\dfrac{1}{3}$是( )个
4个梨是这些梨的$\dfrac{( )}{( )}$
没涂色的苹果是这些苹果的$\dfrac{( )}{( )}$,是( )个。

1.（1）3 4 10 （2）$\frac{5}{8}$ 2 3 5 $\frac{5}{8}$ （3）$\frac{4}{6}$ 6 2 4 $\frac{1}{6}$ $\frac{4}{6}$ （4）2 $\frac{2}{5}$ $\frac{1}{4}$ 2

2 算一算。
$\begin{array}{l}\dfrac{3}{8} \\\dfrac{1}{8} \\\dfrac{3}{8}+ \dfrac{5}{8} \\\dfrac{2}{8} \\\dfrac{4}{8}\end{array} $
$=$
$\begin{array}{l}\ \\\ \\\ \\\ \\\ \end{array}\begin{array}{l}\ \\\ \\\ \\\ \\\ $
$1-$
$\begin{array}{l}\dfrac{1}{8} \\\dfrac{3}{5} \\\dfrac{5}{9} \\\dfrac{2}{6} \\\dfrac{4}{7}\end{array} $
$=$
$\begin{array}{l}\ \\\ \\\ \\\ \\\ \end{array}\begin{array}{l}\ \\\ \\\ \\\ \\\ $

$\frac{6}{8}$ $\frac{4}{8}$ $\frac{8}{8}$ $\frac{5}{8}$ $\frac{7}{8}$ $\frac{7}{8}$ $\frac{2}{5}$ $\frac{4}{9}$ $\frac{4}{6}$ $\frac{3}{7}$

$\dfrac{3}{8}+\dfrac{3}{8}=\dfrac{6}{8}$
$\dfrac{3}{8}+\dfrac{1}{8}=\dfrac{4}{8}$
$\dfrac{3}{8}+\dfrac{5}{8}=\dfrac{8}{8}$
$\dfrac{3}{8}+\dfrac{2}{8}=\dfrac{5}{8}$
$\dfrac{3}{8}+\dfrac{4}{8}=\dfrac{7}{8}$
$1-\dfrac{1}{8}=\dfrac{7}{8}$
$1-\dfrac{3}{5}=\dfrac{2}{5}$
$1-\dfrac{5}{9}=\dfrac{4}{9}$
$1-\dfrac{2}{6}=\dfrac{4}{6}$
$1-\dfrac{4}{7}=\dfrac{3}{7}$

3 举办联欢会需要$45$个气球,陈叔叔第一次吹好了总个数的$\dfrac{3}{5}$,第二次吹好了总个数的$\dfrac{1}{5}$,一共吹好了几个气球？

36个

$45×\left(\dfrac{3}{5}+\dfrac{1}{5}\right)=45×\dfrac{4}{5}=36$（个）
答：一共吹好了36个气球。