I can discern you can discern she can discern we can discern you can discern they can discern
V-ing form
I can be discerning you can be discerning she can be discerning we can be discerning you can be discerning they can be discerning
Perfect
I can have discerned you can have discerned she 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 she 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 she cannot discern we cannot discern you cannot discern they cannot discern
V-ing form
I cannot be discerning you cannot be discerning she cannot be discerning we cannot be discerning you cannot be discerning they cannot be discerning
Perfect
I cannot have discerned you cannot have discerned she 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 she 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 she discern? can we discern? can you discern? can they discern?
V-ing form
can I be discerning? can you be discerning? can she be discerning? can we be discerning? can you be discerning? can they be discerning?
Perfect
can I have discerned? can you have discerned? can she 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 she 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 she 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 she 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 she 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 she not have been discerning? can we not have been discerning? can you not have been discerning? can they not have been discerning?