a$)$ Show that $\text{'}\text{'}$ and $\text{'}\text{'}$ form a functionally complete collection of logical operators.

b$)$ Let C$($x$),$ D$($x$),$ and E$($x$)$ be the statements $"$x is a contractor," $"$x is dependable $,"$ and $"$x is an engineer," respectively. Express each of the following statements using quantifiers, logical connectives, and C$($x$),$ S$($x$),$ and E$($x$).$

$($i$)$ No contractors are dependable.

$($ii$)$ Some contractors are engineers.

$($iii$)$ Some engineers are not dependable. Does $($iii$)$ follow from $($i$)$ and $($ii$)?$ Justify your answer.

Please solve this as I need to write this in my assignment.