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.