I was confused by usage of be supposed to and ought to modals. Where can we use them? For instance, I am supposed to/ought to learn English today. I don't have to learn english today, but to me it would be very useful if I learned English today because I could improme my skill. I suspuect that ought to is more suitable here, isn't it?
Another example, I ought to/am supposed to meet my friend in the railway station today. Here is more suitable am supposed to, because it would be amoral if I didn't meet my friend, especially if ti has been arranged earlier.
Is it correct? I'd like you explain me those constructions in details, please :)