Draw the syntax tree for each of the following expressions.

$($a$)($P $$Q$)($P $$ Q$)$

$($b$)($P $$Q$)($P $$ Q$)$

$($c$)$ P $($Q $$ R $->$ P $)($R $->$Q$)$

$($d$)($A $->$ B$)($C $$ D$)($E $->$ F $)$