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