That must be a really big deal.
( That ( ( must ( be ( a ( ( really big ) deal ) ) ) ) . ) )
(ROOT (S (NP (DT That)) (VP (MD must) (VP (VB be) (NP (DT a) (ADJP (RB really) (JJ big)) (NN deal)))) (. .)))
That is very unusual so it must cause a big reaction.
( That ( ( ( is ( very unusual ) ) ( so ( it ( must ( cause ( a ( big reaction ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT That)) (VP (VBZ is) (ADJP (RB very) (JJ unusual)) (SBAR (IN so) (S (NP (PRP it)) (VP (MD must) (VP (VB cause) (NP (DT a) (JJ big) (NN reaction))))))) (. .)))