can sharpen
Regular verb: sharpen - sharpened- sharpened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can sharpen
you can sharpen
he can sharpen
we can sharpen
you can sharpen
they can sharpen 	I can be sharpening
you can be sharpening
he can be sharpening
we can be sharpening
you can be sharpening
they can be sharpening	I can have sharpened
you can have sharpened
he can have sharpened
we can have sharpened
you can have sharpened
they can have sharpened	I can have been sharpening
you can have been sharpening
he can have been sharpening
we can have been sharpening
you can have been sharpening
they can have been sharpening	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't sharpen
you can't sharpen
he can't sharpen
we can't sharpen
you can't sharpen
they can't sharpen 	I can't be sharpening
you can't be sharpening
he can't be sharpening
we can't be sharpening
you can't be sharpening
they can't be sharpening	I can't have sharpened
you can't have sharpened
he can't have sharpened
we can't have sharpened
you can't have sharpened
they can't have sharpened	I can't have been sharpening
you can't have been sharpening
he can't have been sharpening
we can't have been sharpening
you can't have been sharpening
they can't have been sharpening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I sharpen?
can you sharpen?
can he sharpen?
can we sharpen?
can you sharpen?
can they sharpen? 	can I be sharpening?
can you be sharpening?
can he be sharpening?
can we be sharpening?
can you be sharpening?
can they be sharpening? 	can I have sharpened?
can you have sharpened?
can he have sharpened?
can we have sharpened?
can you have sharpened?
can they have sharpened? 	can I have been sharpening?
can you have been sharpening?
can he have been sharpening?
can we have been sharpening?
can you have been sharpening?
can they have been sharpening? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I sharpen?
can't you sharpen?
can't he sharpen?
can't we sharpen?
can't you sharpen?
can't they sharpen? 	can't I be sharpening?
can't you be sharpening?
can't he be sharpening?
can't we be sharpening?
can't you be sharpening?
can't they be sharpening? 	can't I have sharpened?
can't you have sharpened?
can't he have sharpened?
can't we have sharpened?
can't you have sharpened?
can't they have sharpened? 	can't I have been sharpening?
can't you have been sharpening?
can't he have been sharpening?
can't we have been sharpening?
can't you have been sharpening?
can't they have been sharpening?