We cannot.
10. Why?
Because there are too many exceptions.
11. What makes a rule in Orthography?
Whenever a letter is silent, or usually so, a rule is formed.
12. Why is c placed before r in acre, massacre, etc.?
To preserve the hard sound of c.
13. What is the rule for Digraphs?
A digraph must have one vowel silent.
14. Give rule for E final.