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 couldn't tier you couldn't tier he couldn't tier we couldn't tier you couldn't tier they couldn't tier	I couldn't be tiering you couldn't be tiering he couldn't be tiering we couldn't be tiering you couldn't be tiering they couldn't be tiering
Perfect	V-ing perfect
I couldn't have tiered you couldn't have tiered he couldn't have tiered we couldn't have tiered you couldn't have tiered they couldn't have tiered	I couldn't have been tiering you couldn't have been tiering he couldn't have been tiering we couldn't have been tiering you couldn't have been tiering they couldn't 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
couldn't I tier? couldn't you tier? couldn't he tier? couldn't we tier? couldn't you tier? couldn't they tier?	couldn't I be tiering? couldn't you be tiering? couldn't he be tiering? couldn't we be tiering? couldn't you be tiering? couldn't they be tiering?
Perfect	V-ing perfect
couldn't I have tiered? couldn't you have tiered? couldn't he have tiered? couldn't we have tiered? couldn't you have tiered? couldn't they have tiered?	couldn't I have been tiering? couldn't you have been tiering? couldn't he have been tiering? couldn't we have been tiering? couldn't you have been tiering? couldn't they have been tiering?