These are in turn surrounded and supported by holders of school certificates and other qualifications.
( These ( ( are ( in ( turn ( ( ( surrounded and ) supported ) ( by ( holders ( of ( ( ( school certificates ) and ) ( other qualifications ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT These)) (VP (VBP are) (PP (IN in) (NP (NP (NN turn)) (VP (VBN surrounded) (CC and) (VBN supported) (PP (IN by) (NP (NP (NNS holders)) (PP (IN of) (NP (NP (NN school) (NNS certificates)) (CC and) (NP (JJ other) (NNS qualifications)))))))))) (. .)))
Holders of school certificates provide a vital support structure.
( ( Holders ( of ( school certificates ) ) ) ( ( provide ( a ( vital ( support structure ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Holders)) (PP (IN of) (NP (NN school) (NNS certificates)))) (VP (VBP provide) (NP (DT a) (JJ vital) (NN support) (NN structure))) (. .)))