English verb conjugation
CAN STUMBLE

Regular verb: stumble - stumbled - stumbled

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
I cannot stumble you cannot stumble he cannot stumble we cannot stumble you cannot stumble they cannot stumble	I cannot be stumbling you cannot be stumbling he cannot be stumbling we cannot be stumbling you cannot be stumbling they cannot be stumbling
Perfect	V-ing perfect
I cannot have stumbled you cannot have stumbled he cannot have stumbled we cannot have stumbled you cannot have stumbled they cannot have stumbled	I cannot have been stumbling you cannot have been stumbling he cannot have been stumbling we cannot have been stumbling you cannot have been stumbling they cannot have been stumbling

Interrogative form

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