( Organs ( ( are ( ( units ( of ( ( structure and ) function ) ) ) ( that ( are ( composed ( of ( ( ( ( ( at least ) two ) , ) and ) ( usually ( ( ( all four ) , ) ( primary tissues ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Organs)) (VP (VBP are) (NP (NP (NNS units)) (PP (IN of) (NP (NN structure) (CC and) (NN function))) (SBAR (WHNP (WDT that)) (S (VP (VBP are) (VP (VBN composed) (PP (IN of) (NP (NP (QP (IN at) (JJS least) (CD two))) (, ,) (CC and) (NP (ADVP (RB usually)) (NP (DT all) (CD four)) (, ,) (NP (JJ primary) (NNS tissues))))))))))) (. .)))
Organs are units of structure and function that are composed of at least two, and usually all four, primary tissues.
(ROOT (S (NP (DT A) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN organ)) (VP (VBZ is) (NP (NP (DT a) (NN structure)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (VP (VBN composed) (PP (IN of) (NP (NP (QP (CD one) (CC or) (JJR more)) (NNS types)) (PP (IN of) (NP (NNS tissues))))))))))) (. .)))
A(n) organ is a structure that is composed of one or more types of tissues.