Is there any difference?
1. I spend 2 hours a day studying English.
2. I spend 2 hours per day studying English.
3. I spend 2 hours studying English every day.
Thank you.
1. Sounds natural. No main emphasis on the act of studying.
2. Understandable but using "per day" sounds unnatural to me.
3. Sounds natural. Using the continuous form places some emphasis on the time that you spend studying.