It naturally follows from the definition of the Continuous form (“it denotes an action in a state of process at the present moment or at a definite moment in the past or future”) that verbs which do not express a process are not used in the continuous form.
The following groups of verbs do not not express a process.
(a) verbs denoting sense perception (to see, to hear);
Note: The verb “to feel” is an exception. It is often used in the Continuous form.
(b) verbs denoting mental activity (to know, to believe);
(c) verbs denoting wish (to want, to wish);
(d) verbs denoting feeling (to love, to hate, to like);
(e) verbs denoting abstract relations (to have, to consist, to depend, to belong).
In such expressions as to see the sights of, to see somebody home, to set somebody off the verb to see does not mean ‘бачити', so it can be used in the Continuous form.
It is naturally possible to use the Continuous form of the verb to have in the expressions of the type to have dinner (lunch, supper) because it does not denote possession.
They are having lunch.
The verb to think cannot be used in the Continuous form if it denotes an opinion, it can if it denotes a process of thought.
I am thinking of what you have just said.
