The answer is a you can use a imperfecto chart
1. si, hay formas diferentes de la bandera (yes, there were different forms of the flag)
Why have the changes been made?
I didn’t find answer for this question
2. La bandera de México es un símbolo muy importante para todos los mexicanos que se ejemplifica el Día de la Bandera.
I did this when I was in Chem :)
Face changes in matter means that the matter changes from one of the following states to another.
Gas, Liquid, and Solid.
When heat is added to a solid it becomes a liquid, when head is added to liquid it becomes a solid.
This chart helps.