  Remote brightenings often appear at outskirts of source active regions of
solar eruptive events, nevertheless, their origin remains to be ascertained. In
this study, we report imaging and spectroscopic observations of sequential
remote brightenings with a combination of H$\alpha$ Imaging Spectrograph (HIS)
onboard the Chinese H$\alpha$ Solar Explorer (CHASE), which is the first
space-based solar telescope of China, and the Solar Dynamics Observatory. It is
found that, during two successive M-class flares occurring on 2022 August 17,
multiple ribbon-like brightenings appeared in sequence away from the flaring
active region. Meanwhile, abundant cool filament materials moved downward to
the sequential remote brightenings as visible at the H$\alpha$ red wing with a
line-of-sight speed up to 70 km s$^{-1}$. The extrapolated three-dimensional
magnetic field configuration shows that the sequential remote brightenings
correspond to the footpoints of closed ambient field lines whose conjugate
footpoints are rooted in the main flare site. We suggest that the sequential
remote brightenings are most likely caused by the heating of interchange
reconnection between the erupting flux rope and closed ambient field, during
which the rope-hosting filament materials are transferred to the periphery of
flaring active region along the closed ambient field rather than to the
interplanetary space like in the scenario of the slow solar wind formation.
