S -> NP VP
S -> VP
S -> X1 PP
X1 -> NP VP
NP -> Det N
NP -> Poss N
NP -> PN
NP -> Prn
NP -> NP PP
PP -> P NP
VP -> V
VP -> V NP
VP -> VP PP
N -> "book"
N -> "flight"
N -> "elephant"
N -> "pajamas"
N -> "shot"
V -> "book"
V -> "booked"
V -> "shoot"
V -> "shot"
PN -> "Houston"
P -> "in"
P -> "through"
Det -> "the"
Det -> "an"
Det -> "a"
Poss -> "my"
Prn -> "I"