English verb conjugation
CAN TIFF

Regular verb: tiff - tiffed - tiffed

Affirmation

Simple form	V-ing form
I can tiff you can tiff he can tiff we can tiff you can tiff they can tiff	I can be tiffing you can be tiffing he can be tiffing we can be tiffing you can be tiffing they can be tiffing
Perfect	V-ing perfect
I can have tiffed you can have tiffed he can have tiffed we can have tiffed you can have tiffed they can have tiffed	I can have been tiffing you can have been tiffing he can have been tiffing we can have been tiffing you can have been tiffing they can have been tiffing

Negation

Simple form	V-ing form
I can't tiff you can't tiff he can't tiff we can't tiff you can't tiff they can't tiff	I can't be tiffing you can't be tiffing he can't be tiffing we can't be tiffing you can't be tiffing they can't be tiffing
Perfect	V-ing perfect
I can't have tiffed you can't have tiffed he can't have tiffed we can't have tiffed you can't have tiffed they can't have tiffed	I can't have been tiffing you can't have been tiffing he can't have been tiffing we can't have been tiffing you can't have been tiffing they can't have been tiffing

Interrogative form

Simple form	V-ing form
can I tiff? can you tiff? can he tiff? can we tiff? can you tiff? can they tiff?	can I be tiffing? can you be tiffing? can he be tiffing? can we be tiffing? can you be tiffing? can they be tiffing?
Perfect	V-ing perfect
can I have tiffed? can you have tiffed? can he have tiffed? can we have tiffed? can you have tiffed? can they have tiffed?	can I have been tiffing? can you have been tiffing? can he have been tiffing? can we have been tiffing? can you have been tiffing? can they have been tiffing?

Interro-negative form

Simple form	V-ing form
can't I tiff? can't you tiff? can't he tiff? can't we tiff? can't you tiff? can't they tiff?	can't I be tiffing? can't you be tiffing? can't he be tiffing? can't we be tiffing? can't you be tiffing? can't they be tiffing?
Perfect	V-ing perfect
can't I have tiffed? can't you have tiffed? can't he have tiffed? can't we have tiffed? can't you have tiffed? can't they have tiffed?	can't I have been tiffing? can't you have been tiffing? can't he have been tiffing? can't we have been tiffing? can't you have been tiffing? can't they have been tiffing?