English for Today
STATIVE AND DYNAMIC VERBS
Verbs have stative and dynamic uses. A stative verb does not  take the -ing form and as such can not be used for the continuous tense whereas dynamic verb can take -ing and be used in the progressive. However, some verbs have both stative and dynamic uses. In the English language, verbs of the sense(feel, hear, ..), links(seem, appear ...). emotion(admire, adore ...) and verbs of mental activity(agree, assume...)  are not normally used in the continuous tense except when they denote some other meanings in structure.
I understand you(right).
I am understanding you(wrong).
We can see the tower from afar(right).
We are seeing the tower from afar(wrong).