English verb conjugation
COULD TIER

Regular verb: tier - tiered - tiered

Affirmation

Simple form	V-ing form
I could tier you could tier he could tier we could tier you could tier they could tier	I could be tiering you could be tiering he could be tiering we could be tiering you could be tiering they could be tiering
Perfect	V-ing perfect
I could have tiered you could have tiered he could have tiered we could have tiered you could have tiered they could have tiered	I could have been tiering you could have been tiering he could have been tiering we could have been tiering you could have been tiering they could have been tiering

Negation

Simple form	V-ing form
I could not tier you could not tier he could not tier we could not tier you could not tier they could not tier	I could not be tiering you could not be tiering he could not be tiering we could not be tiering you could not be tiering they could not be tiering
Perfect	V-ing perfect
I could not have tiered you could not have tiered he could not have tiered we could not have tiered you could not have tiered they could not have tiered	I could not have been tiering you could not have been tiering he could not have been tiering we could not have been tiering you could not have been tiering they could not have been tiering

Interrogative form

Simple form	V-ing form
could I tier? could you tier? could he tier? could we tier? could you tier? could they tier?	could I be tiering? could you be tiering? could he be tiering? could we be tiering? could you be tiering? could they be tiering?
Perfect	V-ing perfect
could I have tiered? could you have tiered? could he have tiered? could we have tiered? could you have tiered? could they have tiered?	could I have been tiering? could you have been tiering? could he have been tiering? could we have been tiering? could you have been tiering? could they have been tiering?

Interro-negative form

Simple form	V-ing form
could I not tier? could you not tier? could he not tier? could we not tier? could you not tier? could they not tier?	could I not be tiering? could you not be tiering? could he not be tiering? could we not be tiering? could you not be tiering? could they not be tiering?
Perfect	V-ing perfect
could I not have tiered? could you not have tiered? could he not have tiered? could we not have tiered? could you not have tiered? could they not have tiered?	could I not have been tiering? could you not have been tiering? could he not have been tiering? could we not have been tiering? could you not have been tiering? could they not have been tiering?