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 can't thumb you can't thumb he can't thumb we can't thumb you can't thumb they can't thumb	I can't be thumbing you can't be thumbing he can't be thumbing we can't be thumbing you can't be thumbing they can't be thumbing
Perfect	V-ing perfect
I can't have thumbed you can't have thumbed he can't have thumbed we can't have thumbed you can't have thumbed they can't have thumbed	I can't have been thumbing you can't have been thumbing he can't have been thumbing we can't have been thumbing you can't have been thumbing they can't 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't I thumb? can't you thumb? can't he thumb? can't we thumb? can't you thumb? can't they thumb?	can't I be thumbing? can't you be thumbing? can't he be thumbing? can't we be thumbing? can't you be thumbing? can't they be thumbing?
Perfect	V-ing perfect
can't I have thumbed? can't you have thumbed? can't he have thumbed? can't we have thumbed? can't you have thumbed? can't they have thumbed?	can't I have been thumbing? can't you have been thumbing? can't he have been thumbing? can't we have been thumbing? can't you have been thumbing? can't they have been thumbing?