English verb conjugation
CAN SKETCH

Regular verb: sketch - sketched - sketched

Affirmation

Simple form	V-ing form
I can sketch you can sketch he can sketch we can sketch you can sketch they can sketch	I can be sketching you can be sketching he can be sketching we can be sketching you can be sketching they can be sketching
Perfect	V-ing perfect
I can have sketched you can have sketched he can have sketched we can have sketched you can have sketched they can have sketched	I can have been sketching you can have been sketching he can have been sketching we can have been sketching you can have been sketching they can have been sketching

Negation

Simple form	V-ing form
I cannot sketch you cannot sketch he cannot sketch we cannot sketch you cannot sketch they cannot sketch	I cannot be sketching you cannot be sketching he cannot be sketching we cannot be sketching you cannot be sketching they cannot be sketching
Perfect	V-ing perfect
I cannot have sketched you cannot have sketched he cannot have sketched we cannot have sketched you cannot have sketched they cannot have sketched	I cannot have been sketching you cannot have been sketching he cannot have been sketching we cannot have been sketching you cannot have been sketching they cannot have been sketching

Interrogative form

Simple form	V-ing form
can I sketch? can you sketch? can he sketch? can we sketch? can you sketch? can they sketch?	can I be sketching? can you be sketching? can he be sketching? can we be sketching? can you be sketching? can they be sketching?
Perfect	V-ing perfect
can I have sketched? can you have sketched? can he have sketched? can we have sketched? can you have sketched? can they have sketched?	can I have been sketching? can you have been sketching? can he have been sketching? can we have been sketching? can you have been sketching? can they have been sketching?

Interro-negative form

Simple form	V-ing form
can I not sketch? can you not sketch? can he not sketch? can we not sketch? can you not sketch? can they not sketch?	can I not be sketching? can you not be sketching? can he not be sketching? can we not be sketching? can you not be sketching? can they not be sketching?
Perfect	V-ing perfect
can I not have sketched? can you not have sketched? can he not have sketched? can we not have sketched? can you not have sketched? can they not have sketched?	can I not have been sketching? can you not have been sketching? can he not have been sketching? can we not have been sketching? can you not have been sketching? can they not have been sketching?