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 can't discern you can't discern he can't discern we can't discern you can't discern they can't discern
V-ing form
I can't be discerning you can't be discerning he can't be discerning we can't be discerning you can't be discerning they can't be discerning
Perfect
I can't have discerned you can't have discerned he can't have discerned we can't have discerned you can't have discerned they can't have discerned
V-ing perfect
I can't have been discerning you can't have been discerning he can't have been discerning we can't have been discerning you can't have been discerning they can't 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't I discern? can't you discern? can't he discern? can't we discern? can't you discern? can't they discern?
V-ing form
can't I be discerning? can't you be discerning? can't he be discerning? can't we be discerning? can't you be discerning? can't they be discerning?
Perfect
can't I have discerned? can't you have discerned? can't he have discerned? can't we have discerned? can't you have discerned? can't they have discerned?
V-ing perfect
can't I have been discerning? can't you have been discerning? can't he have been discerning? can't we have been discerning? can't you have been discerning? can't they have been discerning?