Most of the educated Jews living in Israel at that time spoke Greek as well as Aramaic, since Greek was the common language of the conquered lands, and there were always Jews from foreign parts visiting Israel for religious purposes. And of course some of the Jews could speak as well as read Hebrew.
I think it seems likely that Jesus may have delivered his sayings in several different languages, depending on his audience or other circumstances.
http://en.wikipedia.org/wiki/Language_of_Jesus
Josephus wrote:
I have also taken a great deal of pains to obtain the learning of the Greeks, and understand the elements of the Greek language, although I have so long accustomed myself to speak our own tongue, that I cannot pronounce Greek with sufficient exactness; for our nation does not encourage those that learn the languages of many nations, and so adorn their discourses with the smoothness of their periods; because they look upon this sort of accomplishment as common, not only to all sorts of free-men, but to as many of the servants as please to learn them. But they give him the testimony of being a wise man who is fully acquainted with our laws, and is able to interpret their meaning; on which account, as there have been many who have done their endeavors with great patience to obtain this learning, there have yet hardly been so many as two or three that have succeeded therein, who were immediately well rewarded for their pains.
—Antiquities of Jews XX, XI