( ( ( This combination ) ( of drugs ) ) ( ( can ( ( cause sunburns ) ( if ( ( in ( the sun ) ) directly ) ) ) ) . ) )
(ROOT (S (NP (NP (DT This) (NN combination)) (PP (IN of) (NP (NNS drugs)))) (VP (MD can) (VP (VB cause) (NP (NNS sunburns)) (ADVP (IN if) (PP (IN in) (NP (DT the) (NN sun)) (ADVP (RB directly)))))) (. .)))
This combination of drugs can cause sunburns if in the sun directly.
(ROOT (S (S (VP (VBG Looking) (ADVP (RB directly)) (PP (IN at) (NP (DT the) (NN sun))))) (VP (MD can) (VP (VB cause) (NP (NN blindness)))) (. .)))