can crumble
Regular verb: crumble - crumbled- crumbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can crumble
you can crumble
he can crumble
we can crumble
you can crumble
they can crumble 	I can be crumbling
you can be crumbling
he can be crumbling
we can be crumbling
you can be crumbling
they can be crumbling	I can have crumbled
you can have crumbled
he can have crumbled
we can have crumbled
you can have crumbled
they can have crumbled	I can have been crumbling
you can have been crumbling
he can have been crumbling
we can have been crumbling
you can have been crumbling
they can have been crumbling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't crumble
you can't crumble
he can't crumble
we can't crumble
you can't crumble
they can't crumble 	I can't be crumbling
you can't be crumbling
he can't be crumbling
we can't be crumbling
you can't be crumbling
they can't be crumbling	I can't have crumbled
you can't have crumbled
he can't have crumbled
we can't have crumbled
you can't have crumbled
they can't have crumbled	I can't have been crumbling
you can't have been crumbling
he can't have been crumbling
we can't have been crumbling
you can't have been crumbling
they can't have been crumbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I crumble?
can you crumble?
can he crumble?
can we crumble?
can you crumble?
can they crumble? 	can I be crumbling?
can you be crumbling?
can he be crumbling?
can we be crumbling?
can you be crumbling?
can they be crumbling? 	can I have crumbled?
can you have crumbled?
can he have crumbled?
can we have crumbled?
can you have crumbled?
can they have crumbled? 	can I have been crumbling?
can you have been crumbling?
can he have been crumbling?
can we have been crumbling?
can you have been crumbling?
can they have been crumbling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I crumble?
can't you crumble?
can't he crumble?
can't we crumble?
can't you crumble?
can't they crumble? 	can't I be crumbling?
can't you be crumbling?
can't he be crumbling?
can't we be crumbling?
can't you be crumbling?
can't they be crumbling? 	can't I have crumbled?
can't you have crumbled?
can't he have crumbled?
can't we have crumbled?
can't you have crumbled?
can't they have crumbled? 	can't I have been crumbling?
can't you have been crumbling?
can't he have been crumbling?
can't we have been crumbling?
can't you have been crumbling?
can't they have been crumbling?