Заполни пропуски

1. \(\dfrac{3}{7} \, +\) [ ] \(=1\) ;

2. \(\dfrac{16}{39} \, +\) [ ] \(=1\) ;

3. \(\dfrac{19}{9} \, -\) [ ] \(=1\) ;

4. \(\dfrac{17}{3} \, -\) [ ] \(=1\) .