I'm afraid your expanation is a bit off.
You are correct that we use "how" or "what a" to form exclamations.
However, which you choose does not depend on whether the correesponding
declarative sentence as the word "a" in it.
1. The house is beautiful.
2. How beautiful the house is!
3. What a beautiful house!
Both sentences 2 and 3 are correct.
4. It is a beautiful day.
5. How beautiful the day is!
6. What a beautiful day it is!
Again, both 5 and 6 are correct.
7. These are excellent examples.
8. How excellent these examples are!
9. What excellent examples these are!
This time, sentence 7 does nor use "a," so neither do sentences 8 and 9.
Ravi Rawat wrote:
> While converting assertive sentences to exclamatory sentences we
> generally use How and What.
> Generally if an assertive sentence contains "a" we use "What" in
> exclamatory sentences else How.
> Assertive: It is a beautiful day
> Exclamatory: What a beautiful day it is!
> Assertive: It is very big house.
> Exclamatory: How big the house is!
> Is there a better way to understand conversion of assertive sentences to
> exclamatory sentences.