I can purify you can purify he can purify we can purify you can purify they can purify
V-ing form
I can be purifying you can be purifying he can be purifying we can be purifying you can be purifying they can be purifying
Perfect
I can have purified you can have purified he can have purified we can have purified you can have purified they can have purified
V-ing perfect
I can have been purifying you can have been purifying he can have been purifying we can have been purifying you can have been purifying they can have been purifying
Negation
Simple form
I cannot purify you cannot purify he cannot purify we cannot purify you cannot purify they cannot purify
V-ing form
I cannot be purifying you cannot be purifying he cannot be purifying we cannot be purifying you cannot be purifying they cannot be purifying
Perfect
I cannot have purified you cannot have purified he cannot have purified we cannot have purified you cannot have purified they cannot have purified
V-ing perfect
I cannot have been purifying you cannot have been purifying he cannot have been purifying we cannot have been purifying you cannot have been purifying they cannot have been purifying
Interrogative form
Simple form
can I purify? can you purify? can he purify? can we purify? can you purify? can they purify?
V-ing form
can I be purifying? can you be purifying? can he be purifying? can we be purifying? can you be purifying? can they be purifying?
Perfect
can I have purified? can you have purified? can he have purified? can we have purified? can you have purified? can they have purified?
V-ing perfect
can I have been purifying? can you have been purifying? can he have been purifying? can we have been purifying? can you have been purifying? can they have been purifying?
Interro-negative form
Simple form
can I not purify? can you not purify? can he not purify? can we not purify? can you not purify? can they not purify?
V-ing form
can I not be purifying? can you not be purifying? can he not be purifying? can we not be purifying? can you not be purifying? can they not be purifying?
Perfect
can I not have purified? can you not have purified? can he not have purified? can we not have purified? can you not have purified? can they not have purified?
V-ing perfect
can I not have been purifying? can you not have been purifying? can he not have been purifying? can we not have been purifying? can you not have been purifying? can they not have been purifying?