Abstract: Under the consideration of a tentative unified model of magnetic arch, neutral sheet and arcade, this paper analysis synthetically the observed data of two-ribbon flares and associated phenomena on Feb. 3, 1983. It is shown that there exists a close connection between the physical precesses of nonthermal and thermal emissions in the two-ribbon flares, and, in particular that the nonthermal electrons from source regions of type HI, type IVμ and other type IVbursts are responsible for hard X-ray and r-ray bursts and H_α bright ribbons while the above mentioned magnetic structures move freely along the vertical direction and horizontal direction.