I can discern you can discern he can discern we can discern you can discern they can discern
V-ing form
I can be discerning you can be discerning he can be discerning we can be discerning you can be discerning they can be discerning
Perfect
I can have discerned you can have discerned he can have discerned we can have discerned you can have discerned they can have discerned
V-ing perfect
I can have been discerning you can have been discerning he can have been discerning we can have been discerning you can have been discerning they can have been discerning
Negation
Simple form
I cannot discern you cannot discern he cannot discern we cannot discern you cannot discern they cannot discern
V-ing form
I cannot be discerning you cannot be discerning he cannot be discerning we cannot be discerning you cannot be discerning they cannot be discerning
Perfect
I cannot have discerned you cannot have discerned he cannot have discerned we cannot have discerned you cannot have discerned they cannot have discerned
V-ing perfect
I cannot have been discerning you cannot have been discerning he cannot have been discerning we cannot have been discerning you cannot have been discerning they cannot have been discerning
Interrogative form
Simple form
can I discern? can you discern? can he discern? can we discern? can you discern? can they discern?
V-ing form
can I be discerning? can you be discerning? can he be discerning? can we be discerning? can you be discerning? can they be discerning?
Perfect
can I have discerned? can you have discerned? can he have discerned? can we have discerned? can you have discerned? can they have discerned?
V-ing perfect
can I have been discerning? can you have been discerning? can he have been discerning? can we have been discerning? can you have been discerning? can they have been discerning?
Interro-negative form
Simple form
can I not discern? can you not discern? can he not discern? can we not discern? can you not discern? can they not discern?
V-ing form
can I not be discerning? can you not be discerning? can he not be discerning? can we not be discerning? can you not be discerning? can they not be discerning?
Perfect
can I not have discerned? can you not have discerned? can he not have discerned? can we not have discerned? can you not have discerned? can they not have discerned?
V-ing perfect
can I not have been discerning? can you not have been discerning? can he not have been discerning? can we not have been discerning? can you not have been discerning? can they not have been discerning?