( ( ( ( ( ( ( The eyes ) , ) ears ) , ) and ) ( ( respiratory system ) all ) ) ( ( start ( to ( develop ( at ( 4 weeks ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NNS eyes)) (, ,) (NP (NNS ears)) (, ,) (CC and) (NP (NP (JJ respiratory) (NN system)) (NP (DT all)))) (VP (VBP start) (S (VP (TO to) (VP (VB develop) (PP (IN at) (NP (CD 4) (NNS weeks))))))) (. .)))
The eyes, ears, and respiratory system all start to develop at 4 weeks.
(ROOT (S (NP (NP (DT The) (NN development)) (PP (IN of) (NP (NP (DT the) (JJ respiratory) (NN system)) (PP (IN in) (NP (DT the) (NN fetus)))))) (VP (VBZ begins) (PP (IN at) (NP (QP (RB about) (CD 4)) (NNS weeks)))) (. .)))
The development of the respiratory system in the fetus begins at about 4 weeks.