Have or having? May the verb "HAVE" be used in the Continuous Form?
In my Gramma Book there is task - "Put the verb into the correct form"
They_____(be) in the cafe. They_______(have) their breakfast.
I put the verbs as below:
They are in the cafe. They have their breakfast.
But, in the keys to this task this sentence is showed as below:
They are in the cafe. They are having their breakfast.
Till now, I thought that verb "have" can't be use at the Continuous Form, because in my Grammar book there is an exeption for this verb in Present Continuous Topic. This exeption says "Verbs denoting abstract ralations - to be, TO HAVE, to contain...etc." don't use in the Continuous Form. Also there is addition to this statement - "the groups of verbs do not express a process.". Also, on YouTube I saw the lesson about verbs, where it was said that verbs devides on tow groups -- state verbs and action verbs, and state verbs never used in the Continuous Form.
So, is it mean that in my sentence the verb "have" is not state verb? Maybe expression "have breakfast" is like idiom?