Type Ⅱ radio bursts aregenerally believed to beexcited by energetic electrons that are accelerated at solar eruption-driven shocks. However, to date the exact locations of radio emission with respect to the shock front and mechanisms of complicated fine structures observed in type Ⅱ spectraare still not well known. In some recent studies, streamers have been suspected to be important on the generation of type Ⅱ radio bursts and the morphology of radio dynamic spectra.