I can fax you can fax he can fax we can fax you can fax they can fax
V-ing form
I can be faxing you can be faxing he can be faxing we can be faxing you can be faxing they can be faxing
Perfect
I can have faxed you can have faxed he can have faxed we can have faxed you can have faxed they can have faxed
V-ing perfect
I can have been faxing you can have been faxing he can have been faxing we can have been faxing you can have been faxing they can have been faxing
Negation
Simple form
I cannot fax you cannot fax he cannot fax we cannot fax you cannot fax they cannot fax
V-ing form
I cannot be faxing you cannot be faxing he cannot be faxing we cannot be faxing you cannot be faxing they cannot be faxing
Perfect
I cannot have faxed you cannot have faxed he cannot have faxed we cannot have faxed you cannot have faxed they cannot have faxed
V-ing perfect
I cannot have been faxing you cannot have been faxing he cannot have been faxing we cannot have been faxing you cannot have been faxing they cannot have been faxing
Interrogative form
Simple form
can I fax? can you fax? can he fax? can we fax? can you fax? can they fax?
V-ing form
can I be faxing? can you be faxing? can he be faxing? can we be faxing? can you be faxing? can they be faxing?
Perfect
can I have faxed? can you have faxed? can he have faxed? can we have faxed? can you have faxed? can they have faxed?
V-ing perfect
can I have been faxing? can you have been faxing? can he have been faxing? can we have been faxing? can you have been faxing? can they have been faxing?
Interro-negative form
Simple form
can I not fax? can you not fax? can he not fax? can we not fax? can you not fax? can they not fax?
V-ing form
can I not be faxing? can you not be faxing? can he not be faxing? can we not be faxing? can you not be faxing? can they not be faxing?
Perfect
can I not have faxed? can you not have faxed? can he not have faxed? can we not have faxed? can you not have faxed? can they not have faxed?
V-ing perfect
can I not have been faxing? can you not have been faxing? can he not have been faxing? can we not have been faxing? can you not have been faxing? can they not have been faxing?