Can we open file made in Dreamweaver CS5 in Dreamweaver CS3?

availablenot Asked: Can we open file made in Dreamweaver CS5 in Dreamweaver CS3?

Just like the title, I wanna ask to make sure if we can open a Dreamweaver CS5's file in Dreamweaver CS3? Can we continue to work on it? Like,if I had started to make a website in Dreamweaver CS5, then when I bring it to another computer with DrwCS3, can I open and continue working on it? What about Dreamweaver CS4 -> CS3, is that possible?