can yak
Regular verb: yak - yaked- yaked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can yak
you can yak
he can yak
we can yak
you can yak
they can yak 	I can be yaking
you can be yaking
he can be yaking
we can be yaking
you can be yaking
they can be yaking	I can have yaked
you can have yaked
he can have yaked
we can have yaked
you can have yaked
they can have yaked	I can have been yaking
you can have been yaking
he can have been yaking
we can have been yaking
you can have been yaking
they can have been yaking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't yak
you can't yak
he can't yak
we can't yak
you can't yak
they can't yak 	I can't be yaking
you can't be yaking
he can't be yaking
we can't be yaking
you can't be yaking
they can't be yaking	I can't have yaked
you can't have yaked
he can't have yaked
we can't have yaked
you can't have yaked
they can't have yaked	I can't have been yaking
you can't have been yaking
he can't have been yaking
we can't have been yaking
you can't have been yaking
they can't have been yaking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I yak?
can you yak?
can he yak?
can we yak?
can you yak?
can they yak? 	can I be yaking?
can you be yaking?
can he be yaking?
can we be yaking?
can you be yaking?
can they be yaking? 	can I have yaked?
can you have yaked?
can he have yaked?
can we have yaked?
can you have yaked?
can they have yaked? 	can I have been yaking?
can you have been yaking?
can he have been yaking?
can we have been yaking?
can you have been yaking?
can they have been yaking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I yak?
can't you yak?
can't he yak?
can't we yak?
can't you yak?
can't they yak? 	can't I be yaking?
can't you be yaking?
can't he be yaking?
can't we be yaking?
can't you be yaking?
can't they be yaking? 	can't I have yaked?
can't you have yaked?
can't he have yaked?
can't we have yaked?
can't you have yaked?
can't they have yaked? 	can't I have been yaking?
can't you have been yaking?
can't he have been yaking?
can't we have been yaking?
can't you have been yaking?
can't they have been yaking?