\[\boxed{\mathbf{Проверочная\ работа\ №1.\ Действие\ деления\ }}\]
\[\boxed{\mathbf{1.}}\]
\[\frac{19}{57} = \frac{1}{3}.\]
\[\boxed{\mathbf{2.}}\]
\[2\frac{1}{9} = \frac{19}{9}.\]
\[\boxed{\mathbf{3.}}\]
\[1\frac{5}{6} = \frac{11}{6} \rightarrow \frac{6}{11}.\]
\[\boxed{\mathbf{4.}}\]
\[\frac{7}{8}\ :7 = \frac{7}{8} \cdot \frac{1}{7} = \frac{1}{8}.\]
\[\boxed{\mathbf{5.}}\]
\[3\ :12 = \frac{3}{12} = \frac{1}{4}.\]
\[\boxed{\mathbf{6.}}\]
\[\frac{1}{5}\ :\frac{1}{3} = \frac{1}{5} \cdot 3 = \frac{3}{5}.\]
\[\boxed{\mathbf{7.}}\]
\[\frac{2}{7}\ :y = \frac{4}{7}\]
\[y = \frac{2}{7}\ :\frac{4}{7} = \frac{2}{7} \cdot \frac{7}{4}\]
\[y = \frac{1}{2}.\]
\[Да.\]
\[\boxed{\mathbf{8.}}\]
\[\mathbf{Да.}\]