( ( ( All strings ) ( containing ( ( ( at least ) two ) ( a 's ) ) ) ) . )
(ROOT (NP (NP (DT All) (NNS strings)) (VP (VBG containing) (NP (QP (IN at) (JJS least) (CD two)) (NP (NNP a) (POS 's)))) (. .)))
All strings containing at least two a's.
(ROOT (S (NP (DT All) (NNS solutions)) (VP (VBP contain) (NP (QP (IN at) (JJS least) (CD two)) (NNS substances))) (. .)))