Заполни пропуски

1. \(b - a + b + a + b + b =\) [ ] \( b\) .
2. \(x + x - y - x + y + x - y + y - y =\) [ ] \( x\) [ ] \( y\) .
3. \(c - a + b - c - a - b + c - a - c + c - b =\) [ ] \(a\) [ ] \(b\) [ ] \(c\) .
4. \(k - n + n + k - p - k + n - p + n - k - p + k =\) [ ] \(k\) [ ] \(n\) [ ] \(p\) .