(S (S (BASENP (DT This) (JJ abrupt) (NN stop)) (VP (VBD created) (BASENP (DT a) (NN hole))) (PP (IN in) (NP (BASENP (DT the) (NN sightglass)) (SBAR (WHNP (WDT which)) (S (VP (VBZ helps) (S (VP (VB monitor) (BASENP (NN fuel) (NNS levels)))))))))) (PERIOD .))