As far as I am aware, we don't have circumfix morphemes in English. Circumfix morphemes wrap around the root of the word. You put one morpheme at the beginning and one at the end in order to make a SINGLE change. For example, in German, to make a past participle of a regular verb, you take the root of the verb, add 'ge' at the beginning and 't' at the end. Those are circumfix morphemes, because the 'ge' and the 't' work together as part of the same grammatical transformation. 'Unbreakable' is different. The 'un' (a prefix) and the 'able' (a suffix) are unrelated. They do different jobs. You make the adjective 'breakable' by adding 'able' to the verb 'break'. The word 'breakable' exists on its own. You can make the adjective negative by adding the prefix 'un', if you want, but you don't have to. Neither of these morphemes depends on the other.

I hope I am answering this one correctly for you - Apologies if not as I am not 100% sure of this either "Un" and "able" are the static morphemes in this relationship because "break" is dynamic So you end up with Un-break-able or unbreakable Un requires a suffix such as Un-do, -able (referencing ability) can be prefixed such as unstop-able Hope it helps :) M