I can undertain you can undertain she can undertain we can undertain you can undertain they can undertain
V-ing form
I can be undertaining you can be undertaining she can be undertaining we can be undertaining you can be undertaining they can be undertaining
Perfect
I can have undertained you can have undertained she can have undertained we can have undertained you can have undertained they can have undertained
V-ing perfect
I can have been undertaining you can have been undertaining she can have been undertaining we can have been undertaining you can have been undertaining they can have been undertaining
Negation
Simple form
I cannot undertain you cannot undertain she cannot undertain we cannot undertain you cannot undertain they cannot undertain
V-ing form
I cannot be undertaining you cannot be undertaining she cannot be undertaining we cannot be undertaining you cannot be undertaining they cannot be undertaining
Perfect
I cannot have undertained you cannot have undertained she cannot have undertained we cannot have undertained you cannot have undertained they cannot have undertained
V-ing perfect
I cannot have been undertaining you cannot have been undertaining she cannot have been undertaining we cannot have been undertaining you cannot have been undertaining they cannot have been undertaining
Interrogative form
Simple form
can I undertain? can you undertain? can she undertain? can we undertain? can you undertain? can they undertain?
V-ing form
can I be undertaining? can you be undertaining? can she be undertaining? can we be undertaining? can you be undertaining? can they be undertaining?
Perfect
can I have undertained? can you have undertained? can she have undertained? can we have undertained? can you have undertained? can they have undertained?
V-ing perfect
can I have been undertaining? can you have been undertaining? can she have been undertaining? can we have been undertaining? can you have been undertaining? can they have been undertaining?
Interro-negative form
Simple form
can I not undertain? can you not undertain? can she not undertain? can we not undertain? can you not undertain? can they not undertain?
V-ing form
can I not be undertaining? can you not be undertaining? can she not be undertaining? can we not be undertaining? can you not be undertaining? can they not be undertaining?
Perfect
can I not have undertained? can you not have undertained? can she not have undertained? can we not have undertained? can you not have undertained? can they not have undertained?
V-ing perfect
can I not have been undertaining? can you not have been undertaining? can she not have been undertaining? can we not have been undertaining? can you not have been undertaining? can they not have been undertaining?