English verb conjugation
COULD CLUSTER

Regular verb: cluster - clustered - clustered

Affirmation

Simple form	V-ing form
I could cluster you could cluster she could cluster we could cluster you could cluster they could cluster	I could be clustering you could be clustering she could be clustering we could be clustering you could be clustering they could be clustering
Perfect	V-ing perfect
I could have clustered you could have clustered she could have clustered we could have clustered you could have clustered they could have clustered	I could have been clustering you could have been clustering she could have been clustering we could have been clustering you could have been clustering they could have been clustering

Negation

Simple form	V-ing form
I couldn't cluster you couldn't cluster she couldn't cluster we couldn't cluster you couldn't cluster they couldn't cluster	I couldn't be clustering you couldn't be clustering she couldn't be clustering we couldn't be clustering you couldn't be clustering they couldn't be clustering
Perfect	V-ing perfect
I couldn't have clustered you couldn't have clustered she couldn't have clustered we couldn't have clustered you couldn't have clustered they couldn't have clustered	I couldn't have been clustering you couldn't have been clustering she couldn't have been clustering we couldn't have been clustering you couldn't have been clustering they couldn't have been clustering

Interrogative form

Simple form	V-ing form
could I cluster? could you cluster? could she cluster? could we cluster? could you cluster? could they cluster?	could I be clustering? could you be clustering? could she be clustering? could we be clustering? could you be clustering? could they be clustering?
Perfect	V-ing perfect
could I have clustered? could you have clustered? could she have clustered? could we have clustered? could you have clustered? could they have clustered?	could I have been clustering? could you have been clustering? could she have been clustering? could we have been clustering? could you have been clustering? could they have been clustering?

Interro-negative form

Simple form	V-ing form
couldn't I cluster? couldn't you cluster? couldn't she cluster? couldn't we cluster? couldn't you cluster? couldn't they cluster?	couldn't I be clustering? couldn't you be clustering? couldn't she be clustering? couldn't we be clustering? couldn't you be clustering? couldn't they be clustering?
Perfect	V-ing perfect
couldn't I have clustered? couldn't you have clustered? couldn't she have clustered? couldn't we have clustered? couldn't you have clustered? couldn't they have clustered?	couldn't I have been clustering? couldn't you have been clustering? couldn't she have been clustering? couldn't we have been clustering? couldn't you have been clustering? couldn't they have been clustering?