can sharpen
Regular verb: sharpen - sharpened- sharpened

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can sharpen
you can sharpen
she can sharpen
we can sharpen
you can sharpen
they can sharpen 	I can be sharpening
you can be sharpening
she can be sharpening
we can be sharpening
you can be sharpening
they can be sharpening	I can have sharpened
you can have sharpened
she 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
she 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 cannot sharpen
you cannot sharpen
she cannot sharpen
we cannot sharpen
you cannot sharpen
they cannot sharpen 	I cannot be sharpening
you cannot be sharpening
she cannot be sharpening
we cannot be sharpening
you cannot be sharpening
they cannot be sharpening	I cannot have sharpened
you cannot have sharpened
she cannot have sharpened
we cannot have sharpened
you cannot have sharpened
they cannot have sharpened	I cannot have been sharpening
you cannot have been sharpening
she cannot have been sharpening
we cannot have been sharpening
you cannot have been sharpening
they cannot have been sharpening	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I sharpen?
can you sharpen?
can she sharpen?
can we sharpen?
can you sharpen?
can they sharpen? 	can I be sharpening?
can you be sharpening?
can she be sharpening?
can we be sharpening?
can you be sharpening?
can they be sharpening? 	can I have sharpened?
can you have sharpened?
can she 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 she 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 I not sharpen?
can you not sharpen?
can she not sharpen?
can we not sharpen?
can you not sharpen?
can they not sharpen? 	can I not be sharpening?
can you not be sharpening?
can she not be sharpening?
can we not be sharpening?
can you not be sharpening?
can they not be sharpening? 	can I not have sharpened?
can you not have sharpened?
can she not have sharpened?
can we not have sharpened?
can you not have sharpened?
can they not have sharpened? 	can I not have been sharpening?
can you not have been sharpening?
can she not have been sharpening?
can we not have been sharpening?
can you not have been sharpening?
can they not have been sharpening?