答案：A
$\begin{array}{cl}
& p^2 -q^2-p-q \\
= & (p+q)(p-q) – (p+q) \\
= & (p+q)(p-q-1)
\end{array}$
$\begin{array}{cl}
& p^2 -q^2-p-q \\
= & (p+q)(p-q) – (p+q) \\
= & (p+q)(p-q-1)
\end{array}$
Resources for HKDSE Mathematics
Resources for HKDSE Mathematics
