1. 直接写出得数。
$\frac{1}{3}+\frac{1}{4}=$
$\frac{1}{5}+\frac{4}{5}=$
$\frac{5}{6}-\frac{1}{3}=$
$\frac{1}{2}-\frac{1}{4}=$
$\frac{7}{8}-\frac{3}{4}=$
$1-\frac{9}{13}=$
$\frac{9}{11}+\frac{3}{11}=$
$\frac{5}{6}-\frac{5}{18}=$
$\frac{7}{10}+\frac{2}{5}=$
$\frac{5}{4}+\frac{3}{4}=$
$\frac{9}{13}-\frac{4}{13}=$
$\frac{4}{9}+\frac{2}{9}=$
$\frac{8}{11}-\frac{5}{11}=$
$\frac{5}{8}-\frac{3}{8}=$
$\frac{7}{15}+\frac{3}{5}=$
$\frac{7}{8}-\frac{2}{8}=$
$\frac{3}{4}+\frac{5}{4}=$
$\frac{3}{7}+\frac{4}{7}=$
$1+\frac{3}{7}=$
$1-\frac{12}{13}=$

$\frac{1}{3}+\frac{1}{4}=\frac{4}{12}+\frac{3}{12}=\frac{7}{12}$
$\frac{1}{5}+\frac{4}{5}=\frac{5}{5}=1$
$\frac{5}{6}-\frac{1}{3}=\frac{5}{6}-\frac{2}{6}=\frac{3}{6}=\frac{1}{2}$
$\frac{1}{2}-\frac{1}{4}=\frac{2}{4}-\frac{1}{4}=\frac{1}{4}$
$\frac{7}{8}-\frac{3}{4}=\frac{7}{8}-\frac{6}{8}=\frac{1}{8}$
$1-\frac{9}{13}=\frac{13}{13}-\frac{9}{13}=\frac{4}{13}$
$\frac{9}{11}+\frac{3}{11}=\frac{12}{11}$
$\frac{5}{6}-\frac{5}{18}=\frac{15}{18}-\frac{5}{18}=\frac{10}{18}=\frac{5}{9}$
$\frac{7}{10}+\frac{2}{5}=\frac{7}{10}+\frac{4}{10}=\frac{11}{10}$
$\frac{5}{4}+\frac{3}{4}=\frac{8}{4}=2$
$\frac{9}{13}-\frac{4}{13}=\frac{5}{13}$
$\frac{4}{9}+\frac{2}{9}=\frac{6}{9}=\frac{2}{3}$
$\frac{8}{11}-\frac{5}{11}=\frac{3}{11}$
$\frac{5}{8}-\frac{3}{8}=\frac{2}{8}=\frac{1}{4}$
$\frac{7}{15}+\frac{3}{5}=\frac{7}{15}+\frac{9}{15}=\frac{16}{15}$
$\frac{7}{8}-\frac{2}{8}=\frac{5}{8}$
$\frac{3}{4}+\frac{5}{4}=\frac{8}{4}=2$
$\frac{3}{7}+\frac{4}{7}=\frac{7}{7}=1$
$1+\frac{3}{7}=\frac{7}{7}+\frac{3}{7}=\frac{10}{7}$
$1-\frac{12}{13}=\frac{13}{13}-\frac{12}{13}=\frac{1}{13}$

2. 填一填。
$\frac{5}{6}-\frac{3}{8}=\frac{(\quad\quad)}{24}-\frac{(\quad\quad)}{24}=\frac{(\quad\quad)}{(\quad\quad)}$

$\frac{3}{4}-\frac{7}{10}=\frac{(\quad\quad)}{20}-\frac{(\quad\quad)}{20}=\frac{(\quad\quad)}{(\quad\quad)}$
$\frac{2}{9}+\frac{5}{12}=\frac{(\quad\quad)}{36}+\frac{(\quad\quad)}{36}=\frac{(\quad\quad)}{(\quad\quad)}$

$\frac{5}{6}-\frac{3}{8}=\frac{20}{24}-\frac{9}{24}=\frac{11}{24}$
$\frac{3}{4}-\frac{7}{10}=\frac{15}{20}-\frac{14}{20}=\frac{1}{20}$
$\frac{2}{9}+\frac{5}{12}=\frac{8}{36}+\frac{15}{36}=\frac{23}{36}$

3. 分数和小数的互化。
(1)把下面的分数化成小数。
$\frac{5}{4}=$
$\frac{7}{80}=$
$\frac{18}{12}=$
$\frac{5}{8}=$

$\frac{21}{15}=$
$\frac{9}{16}=$
$\frac{4}{5}=$
$\frac{15}{6}=$
(2)把下面的小数化成分数。
$0.2=$
$0.15=$
$0.036=$
$0.125=$
$0.375=$
$0.75=$
$3.45=$
$1.08=$

(1)
$\frac{5}{4}=5÷4=1.25$
$\frac{7}{80}=7÷80=0.0875$
$\frac{18}{12}=18÷12=1.5$
$\frac{5}{8}=5÷8=0.625$
$\frac{21}{15}=21÷15=1.4$
$\frac{9}{16}=9÷16=0.5625$
$\frac{4}{5}=4÷5=0.8$
$\frac{15}{6}=15÷6=2.5$
(2)
$0.2=\frac{2}{10}=\frac{1}{5}$
$0.15=\frac{15}{100}=\frac{3}{20}$
$0.036=\frac{36}{1000}=\frac{9}{250}$
$0.125=\frac{125}{1000}=\frac{1}{8}$
$0.375=\frac{375}{1000}=\frac{3}{8}$
$0.75=\frac{75}{100}=\frac{3}{4}$
$3.45=3+\frac{45}{100}=3\frac{9}{20}$
$1.08=1+\frac{8}{100}=1\frac{2}{25}$