But if you do, kill them.
( But ( ( if ( you do ) ) ( , ( ( kill them ) . ) ) ) )
(ROOT (S (CC But) (SBAR (IN if) (S (NP (PRP you)) (VP (VBP do)))) (, ,) (VP (VBP kill) (NP (PRP them))) (. .)))
If the situation is that, you should kill them.
( ( If ( ( the situation ) ( is that ) ) ) ( , ( you ( ( should ( kill them ) ) . ) ) ) )
(ROOT (S (SBAR (IN If) (S (NP (DT the) (NN situation)) (VP (VBZ is) (NP (DT that))))) (, ,) (NP (PRP you)) (VP (MD should) (VP (VB kill) (NP (PRP them)))) (. .)))