( ( Surface tension ) ( ( is ( ( ( what ( permits ( ( ( ( water striders ) and ) ( other insects ) ) ( to ( walk ( across ( ( the surface ) ( of water ) ) ) ) ) ) ) ) and ) ( what ( enables ( a ( needle ( to float ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Surface) (NN tension)) (VP (VBZ is) (NP (SBAR (WHNP (WP what)) (S (VP (VBZ permits) (S (NP (NP (NN water) (NNS striders)) (CC and) (NP (JJ other) (NNS insects))) (VP (TO to) (VP (VB walk) (PP (IN across) (NP (NP (DT the) (NN surface)) (PP (IN of) (NP (NN water))))))))))) (CC and) (SBAR (WHNP (WP what)) (S (VP (VBZ enables) (NP (DT a) (NN needle) (S (VP (TO to) (VP (VB float)))))))))) (. .)))
Surface tension is what permits water striders and other insects to walk across the surface of water and what enables a needle to float.
(ROOT (S (NP (JJ Surface) (NN tension)) (VP (VBZ is) (ADJP (JJ responsible) (PP (IN for) (NP (DT the) (NN fact)))) (SBAR (IN that) (S (NP (JJ small) (NNS insects)) (VP (MD can) (VP (VB walk) (PP (IN on) (NP (NN water)))))))) (. .)))