( ( Scanning ( force ( microscopes ( and ( friction ( force microscopes ) ) ) ) ) ) ( ( are ( built ( in ( ( a ( wide variety ) ) ( of designs ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Scanning) (NN force) (NNS microscopes) (CC and) (NN friction) (NN force) (NNS microscopes)) (VP (VBP are) (VP (VBN built) (PP (IN in) (NP (NP (DT a) (JJ wide) (NN variety)) (PP (IN of) (NP (NNS designs))))))) (. .)))
Scanning force microscopes and friction force microscopes are built in a wide variety of designs.
(ROOT (S (NP (NN Friction) (NN force)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NP (JJ microscopic) (NNS bumps)) (, ,) (VP (VBZ lumps)) (, ,) (CC and) (NP (NP (NNS imperfections)) (VP (VBG colliding))))))) (. .)))