English verb conjugation
COULD ATTEST

Regular verb: attest - attested - attested

Affirmation

Simple form	V-ing form
I could attest you could attest he could attest we could attest you could attest they could attest	I could be attesting you could be attesting he could be attesting we could be attesting you could be attesting they could be attesting
Perfect	V-ing perfect
I could have attested you could have attested he could have attested we could have attested you could have attested they could have attested	I could have been attesting you could have been attesting he could have been attesting we could have been attesting you could have been attesting they could have been attesting

Negation

Simple form	V-ing form
I couldn't attest you couldn't attest he couldn't attest we couldn't attest you couldn't attest they couldn't attest	I couldn't be attesting you couldn't be attesting he couldn't be attesting we couldn't be attesting you couldn't be attesting they couldn't be attesting
Perfect	V-ing perfect
I couldn't have attested you couldn't have attested he couldn't have attested we couldn't have attested you couldn't have attested they couldn't have attested	I couldn't have been attesting you couldn't have been attesting he couldn't have been attesting we couldn't have been attesting you couldn't have been attesting they couldn't have been attesting

Interrogative form

Simple form	V-ing form
could I attest? could you attest? could he attest? could we attest? could you attest? could they attest?	could I be attesting? could you be attesting? could he be attesting? could we be attesting? could you be attesting? could they be attesting?
Perfect	V-ing perfect
could I have attested? could you have attested? could he have attested? could we have attested? could you have attested? could they have attested?	could I have been attesting? could you have been attesting? could he have been attesting? could we have been attesting? could you have been attesting? could they have been attesting?

Interro-negative form

Simple form	V-ing form
couldn't I attest? couldn't you attest? couldn't he attest? couldn't we attest? couldn't you attest? couldn't they attest?	couldn't I be attesting? couldn't you be attesting? couldn't he be attesting? couldn't we be attesting? couldn't you be attesting? couldn't they be attesting?
Perfect	V-ing perfect
couldn't I have attested? couldn't you have attested? couldn't he have attested? couldn't we have attested? couldn't you have attested? couldn't they have attested?	couldn't I have been attesting? couldn't you have been attesting? couldn't he have been attesting? couldn't we have been attesting? couldn't you have been attesting? couldn't they have been attesting?