English verb conjugation
COULD MASK

Regular verb: mask - masked - masked

Affirmation

Simple form	V-ing form
I could mask you could mask he could mask we could mask you could mask they could mask	I could be masking you could be masking he 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 he 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 he 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 he 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 he 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 he 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 he 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 he mask? could we mask? could you mask? could they mask?	could I be masking? could you be masking? could he 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 he 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 he 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 he 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 he 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 he 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 he not have been masking? could we not have been masking? could you not have been masking? could they not have been masking?