\begin{enumerate}
\item[(1)]
$Q \implies R \vdash (P \lor Q) \implies (P \lor R)$.
\item[(2)]
$\vdash ((P \implies Q) \implies P) \implies P$.
\item[(3)]
$(P \implies Q) \land R \vdash (P \land R) \implies (P \land Q)$.
\item[(4)]
$P \land (Q \implies R) \vdash (P \land Q) \implies (P \land R)$.
\end{enumerate}

