(2008? As shown in the figure, a beam of light in the air enters a transparent medium and is reflected and refracted at the interface. Then _ _ _ _ is reflection.

According to the law of reflection, in the absence of light propagation direction, reflected light and incident light should be symmetrical about the normal, so one of HF and HD is incident light, the other is reflected light, AE is normal, and GC is interface;

According to the law of refraction, HB is refracted light, so FH is incident light and HD is reflected light.

So the answer is: HD, HB.