I could conclude you could conclude he could conclude we could conclude you could conclude they could conclude
V-ing form
I could be concluding you could be concluding he could be concluding we could be concluding you could be concluding they could be concluding
Perfect
I could have concluded you could have concluded he could have concluded we could have concluded you could have concluded they could have concluded
V-ing perfect
I could have been concluding you could have been concluding he could have been concluding we could have been concluding you could have been concluding they could have been concluding
Negation
Simple form
I couldn't conclude you couldn't conclude he couldn't conclude we couldn't conclude you couldn't conclude they couldn't conclude
V-ing form
I couldn't be concluding you couldn't be concluding he couldn't be concluding we couldn't be concluding you couldn't be concluding they couldn't be concluding
Perfect
I couldn't have concluded you couldn't have concluded he couldn't have concluded we couldn't have concluded you couldn't have concluded they couldn't have concluded
V-ing perfect
I couldn't have been concluding you couldn't have been concluding he couldn't have been concluding we couldn't have been concluding you couldn't have been concluding they couldn't have been concluding
Interrogative form
Simple form
could I conclude? could you conclude? could he conclude? could we conclude? could you conclude? could they conclude?
V-ing form
could I be concluding? could you be concluding? could he be concluding? could we be concluding? could you be concluding? could they be concluding?
Perfect
could I have concluded? could you have concluded? could he have concluded? could we have concluded? could you have concluded? could they have concluded?
V-ing perfect
could I have been concluding? could you have been concluding? could he have been concluding? could we have been concluding? could you have been concluding? could they have been concluding?
Interro-negative form
Simple form
couldn't I conclude? couldn't you conclude? couldn't he conclude? couldn't we conclude? couldn't you conclude? couldn't they conclude?
V-ing form
couldn't I be concluding? couldn't you be concluding? couldn't he be concluding? couldn't we be concluding? couldn't you be concluding? couldn't they be concluding?
Perfect
couldn't I have concluded? couldn't you have concluded? couldn't he have concluded? couldn't we have concluded? couldn't you have concluded? couldn't they have concluded?
V-ing perfect
couldn't I have been concluding? couldn't you have been concluding? couldn't he have been concluding? couldn't we have been concluding? couldn't you have been concluding? couldn't they have been concluding?