English verb conjugation
CAN THUMB

Regular verb: thumb - thumbed - thumbed

Affirmation

Simple form	V-ing form
I can thumb you can thumb he can thumb we can thumb you can thumb they can thumb	I can be thumbing you can be thumbing he can be thumbing we can be thumbing you can be thumbing they can be thumbing
Perfect	V-ing perfect
I can have thumbed you can have thumbed he can have thumbed we can have thumbed you can have thumbed they can have thumbed	I can have been thumbing you can have been thumbing he can have been thumbing we can have been thumbing you can have been thumbing they can have been thumbing

Negation

Simple form	V-ing form
I cannot thumb you cannot thumb he cannot thumb we cannot thumb you cannot thumb they cannot thumb	I cannot be thumbing you cannot be thumbing he cannot be thumbing we cannot be thumbing you cannot be thumbing they cannot be thumbing
Perfect	V-ing perfect
I cannot have thumbed you cannot have thumbed he cannot have thumbed we cannot have thumbed you cannot have thumbed they cannot have thumbed	I cannot have been thumbing you cannot have been thumbing he cannot have been thumbing we cannot have been thumbing you cannot have been thumbing they cannot have been thumbing

Interrogative form

Simple form	V-ing form
can I thumb? can you thumb? can he thumb? can we thumb? can you thumb? can they thumb?	can I be thumbing? can you be thumbing? can he be thumbing? can we be thumbing? can you be thumbing? can they be thumbing?
Perfect	V-ing perfect
can I have thumbed? can you have thumbed? can he have thumbed? can we have thumbed? can you have thumbed? can they have thumbed?	can I have been thumbing? can you have been thumbing? can he have been thumbing? can we have been thumbing? can you have been thumbing? can they have been thumbing?

Interro-negative form

Simple form	V-ing form
can I not thumb? can you not thumb? can he not thumb? can we not thumb? can you not thumb? can they not thumb?	can I not be thumbing? can you not be thumbing? can he not be thumbing? can we not be thumbing? can you not be thumbing? can they not be thumbing?
Perfect	V-ing perfect
can I not have thumbed? can you not have thumbed? can he not have thumbed? can we not have thumbed? can you not have thumbed? can they not have thumbed?	can I not have been thumbing? can you not have been thumbing? can he not have been thumbing? can we not have been thumbing? can you not have been thumbing? can they not have been thumbing?