Find a formal negation for each of the statements in $($a$)($d$).$

$($a$)$

$$ string s$,$ s has at least one character.

$$ a string s such that s has at least one character.

$$ a string s such that s has exactly one character.

$$ string s$,$ s has exactly one character.

$$ string s$,$ s does not have any characters.

$$ a string s such that s does not have any characters.

$($b$)$

$$ computer c$,$ c has a CPU.

$$ a computer c such that c has more than one CPU.

$$ a computer c such that c does not have a CPU.

$$ a computer c such that c has a CPU.

$$ computer c$,$ c does not have a CPU.

$$ computer c$,$ c has more than one CPU.