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