急! 急! 急!物理 - 折射線問題..

Your teacher is right.

Be aware that light rays do not travel along the dotted-lines shown on the diagram. Because of refraction at the water-air boundary, light rays that come from the object (either the fish in water or the bird in air) reach the eye along some other paths.

Light rays coming out from an object travel in ALL DIRECTIONS. As long as your eyes catch a light ray, you could see the image of the object.

The diagram in the middle of the web-page below gives how light rays coming out from a fish under water are refracted at the surface. You could see that if you eyes are placed at any angle to the water surface, you still can catch a light ray and thus can see the fish. http://www.physics.louisville.edu/cldavis/phys299/notes/lo_tir.html
The diagram in the following link gives a similar picture when the eye is under water. Again, you could see that the eye can see an object flying at any angle above the water surface. No matter at what position the bird is, there is still a light ray enters into the eye. http://www.karinlauphoto.com/compound-lens/images/2460_31_36.jpg
In fact, diagrams A and B are just showing the Principle of Reversibility of Light. If you can see the fish (or bird), the fish (or bird) can see you.