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