HI Nanako,
Sentences 1 and 3 are more alike in that the bankruptcy is only being suggested, so has not generally been acknowledged as being true as it has been in sentence 2.
In sentence 1, "insinuate" is to cast the suggestion in derogatory or accusatory light, even though it is not known to be true.
In sentence 3, "imply" is a more neutral term to introduce the suggestion there might be an impending bankruptcy.
Please let me know if this reply is useful.
-- Norm Guenther