(2) "Chidengyue" is the image of the moon on the water, which belongs to the phenomenon of plane mirror imaging and is formed by the reflection of light.
(3) "The clear water in the pool is shallow" means that the water is clear and the bottom looks shallow, which is due to the refraction of light. Look at the bottom, it is against the direction of light propagation, that is, against the refracted light. Due to the illusion, we always think that light travels along a straight line, so the position we see is shallower than the actual position;
Therefore, the answer is: linear propagation; Reflection; Refraction.