Yesterday i downloaded the macromedia flash 8,before download flash 8,i always use adobe flash cs5.5 to draw stickman,but now i cannot open the adobe flash file using flash 8,it say unexcepted format file,any idea?

That's because flash 8 only supports files wich comes from older flash versions (flash 7,6,5...)

But flash CS 5.5 can support any other file from flash (except for flash CS6 wich is more advanced)

Get it? :D