can croak
Regular verb: croak - croaked- croaked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can croak
you can croak
he can croak
we can croak
you can croak
they can croak 	I can be croaking
you can be croaking
he can be croaking
we can be croaking
you can be croaking
they can be croaking	I can have croaked
you can have croaked
he can have croaked
we can have croaked
you can have croaked
they can have croaked	I can have been croaking
you can have been croaking
he can have been croaking
we can have been croaking
you can have been croaking
they can have been croaking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't croak
you can't croak
he can't croak
we can't croak
you can't croak
they can't croak 	I can't be croaking
you can't be croaking
he can't be croaking
we can't be croaking
you can't be croaking
they can't be croaking	I can't have croaked
you can't have croaked
he can't have croaked
we can't have croaked
you can't have croaked
they can't have croaked	I can't have been croaking
you can't have been croaking
he can't have been croaking
we can't have been croaking
you can't have been croaking
they can't have been croaking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I croak?
can you croak?
can he croak?
can we croak?
can you croak?
can they croak? 	can I be croaking?
can you be croaking?
can he be croaking?
can we be croaking?
can you be croaking?
can they be croaking? 	can I have croaked?
can you have croaked?
can he have croaked?
can we have croaked?
can you have croaked?
can they have croaked? 	can I have been croaking?
can you have been croaking?
can he have been croaking?
can we have been croaking?
can you have been croaking?
can they have been croaking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I croak?
can't you croak?
can't he croak?
can't we croak?
can't you croak?
can't they croak? 	can't I be croaking?
can't you be croaking?
can't he be croaking?
can't we be croaking?
can't you be croaking?
can't they be croaking? 	can't I have croaked?
can't you have croaked?
can't he have croaked?
can't we have croaked?
can't you have croaked?
can't they have croaked? 	can't I have been croaking?
can't you have been croaking?
can't he have been croaking?
can't we have been croaking?
can't you have been croaking?
can't they have been croaking?