English verb conjugation
COULD MASK

Regular verb: mask - masked - masked

Affirmation

Simple form	V-ing form
I could mask you could mask she could mask we could mask you could mask they could mask	I could be masking you could be masking she could be masking we could be masking you could be masking they could be masking
Perfect	V-ing perfect
I could have masked you could have masked she could have masked we could have masked you could have masked they could have masked	I could have been masking you could have been masking she could have been masking we could have been masking you could have been masking they could have been masking

Negation

Simple form	V-ing form
I could not mask you could not mask she could not mask we could not mask you could not mask they could not mask	I could not be masking you could not be masking she could not be masking we could not be masking you could not be masking they could not be masking
Perfect	V-ing perfect
I could not have masked you could not have masked she could not have masked we could not have masked you could not have masked they could not have masked	I could not have been masking you could not have been masking she could not have been masking we could not have been masking you could not have been masking they could not have been masking

Interrogative form

Simple form	V-ing form
could I mask? could you mask? could she mask? could we mask? could you mask? could they mask?	could I be masking? could you be masking? could she be masking? could we be masking? could you be masking? could they be masking?
Perfect	V-ing perfect
could I have masked? could you have masked? could she have masked? could we have masked? could you have masked? could they have masked?	could I have been masking? could you have been masking? could she have been masking? could we have been masking? could you have been masking? could they have been masking?

Interro-negative form

Simple form	V-ing form
could I not mask? could you not mask? could she not mask? could we not mask? could you not mask? could they not mask?	could I not be masking? could you not be masking? could she not be masking? could we not be masking? could you not be masking? could they not be masking?
Perfect	V-ing perfect
could I not have masked? could you not have masked? could she not have masked? could we not have masked? could you not have masked? could they not have masked?	could I not have been masking? could you not have been masking? could she not have been masking? could we not have been masking? could you not have been masking? could they not have been masking?