can stumble
Regular verb: stumble - stumbled- stumbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can stumble
you can stumble
he can stumble
we can stumble
you can stumble
they can stumble 	I can be stumbling
you can be stumbling
he can be stumbling
we can be stumbling
you can be stumbling
they can be stumbling	I can have stumbled
you can have stumbled
he can have stumbled
we can have stumbled
you can have stumbled
they can have stumbled	I can have been stumbling
you can have been stumbling
he can have been stumbling
we can have been stumbling
you can have been stumbling
they can have been stumbling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can't stumble
you can't stumble
he can't stumble
we can't stumble
you can't stumble
they can't stumble 	I can't be stumbling
you can't be stumbling
he can't be stumbling
we can't be stumbling
you can't be stumbling
they can't be stumbling	I can't have stumbled
you can't have stumbled
he can't have stumbled
we can't have stumbled
you can't have stumbled
they can't have stumbled	I can't have been stumbling
you can't have been stumbling
he can't have been stumbling
we can't have been stumbling
you can't have been stumbling
they can't have been stumbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I stumble?
can you stumble?
can he stumble?
can we stumble?
can you stumble?
can they stumble? 	can I be stumbling?
can you be stumbling?
can he be stumbling?
can we be stumbling?
can you be stumbling?
can they be stumbling? 	can I have stumbled?
can you have stumbled?
can he have stumbled?
can we have stumbled?
can you have stumbled?
can they have stumbled? 	can I have been stumbling?
can you have been stumbling?
can he have been stumbling?
can we have been stumbling?
can you have been stumbling?
can they have been stumbling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can't I stumble?
can't you stumble?
can't he stumble?
can't we stumble?
can't you stumble?
can't they stumble? 	can't I be stumbling?
can't you be stumbling?
can't he be stumbling?
can't we be stumbling?
can't you be stumbling?
can't they be stumbling? 	can't I have stumbled?
can't you have stumbled?
can't he have stumbled?
can't we have stumbled?
can't you have stumbled?
can't they have stumbled? 	can't I have been stumbling?
can't you have been stumbling?
can't he have been stumbling?
can't we have been stumbling?
can't you have been stumbling?
can't they have been stumbling?