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