I could ossify you could ossify he could ossify we could ossify you could ossify they could ossify
V-ing form
I could be ossifying you could be ossifying he could be ossifying we could be ossifying you could be ossifying they could be ossifying
Perfect
I could have ossified you could have ossified he could have ossified we could have ossified you could have ossified they could have ossified
V-ing perfect
I could have been ossifying you could have been ossifying he could have been ossifying we could have been ossifying you could have been ossifying they could have been ossifying
Negation
Simple form
I could not ossify you could not ossify he could not ossify we could not ossify you could not ossify they could not ossify
V-ing form
I could not be ossifying you could not be ossifying he could not be ossifying we could not be ossifying you could not be ossifying they could not be ossifying
Perfect
I could not have ossified you could not have ossified he could not have ossified we could not have ossified you could not have ossified they could not have ossified
V-ing perfect
I could not have been ossifying you could not have been ossifying he could not have been ossifying we could not have been ossifying you could not have been ossifying they could not have been ossifying
Interrogative form
Simple form
could I ossify? could you ossify? could he ossify? could we ossify? could you ossify? could they ossify?
V-ing form
could I be ossifying? could you be ossifying? could he be ossifying? could we be ossifying? could you be ossifying? could they be ossifying?
Perfect
could I have ossified? could you have ossified? could he have ossified? could we have ossified? could you have ossified? could they have ossified?
V-ing perfect
could I have been ossifying? could you have been ossifying? could he have been ossifying? could we have been ossifying? could you have been ossifying? could they have been ossifying?
Interro-negative form
Simple form
could I not ossify? could you not ossify? could he not ossify? could we not ossify? could you not ossify? could they not ossify?
V-ing form
could I not be ossifying? could you not be ossifying? could he not be ossifying? could we not be ossifying? could you not be ossifying? could they not be ossifying?
Perfect
could I not have ossified? could you not have ossified? could he not have ossified? could we not have ossified? could you not have ossified? could they not have ossified?
V-ing perfect
could I not have been ossifying? could you not have been ossifying? could he not have been ossifying? could we not have been ossifying? could you not have been ossifying? could they not have been ossifying?