Dear Hasan
Sorry I will write in English as I am at work at the moment & I have free time
The intervals are important in Harmony, as long as you are not writing harmony you may not need it
Composition is very big issue and I wrote some articles already try to re-read again. As this will help you in making new themes from yor intial theme
Greetings
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د.هشام خلف
استشاري طب و جراحة العيون