When light passes from a material of one refractive index to another (for example: from glass to air), it bends.

FIVE SUB GROUPS OF VEGETABLES:-
✔️dark-green vegetables
✔️ starchy vegetable
✔️ red and orange vegetables
✔️ beans and peas
✔️ other vegetables.
HOPE IT HELPS YOU.
They are saying that every theory can eventually be changed a bit due to further research. It does not mean the theory is bad, just that it can become better.