English verb conjugation
COULD BUCKLE

Regular verb: buckle - buckled - buckled

Affirmation

Simple form	V-ing form
I could buckle you could buckle he could buckle we could buckle you could buckle they could buckle	I could be buckling you could be buckling he could be buckling we could be buckling you could be buckling they could be buckling
Perfect	V-ing perfect
I could have buckled you could have buckled he could have buckled we could have buckled you could have buckled they could have buckled	I could have been buckling you could have been buckling he could have been buckling we could have been buckling you could have been buckling they could have been buckling

Negation

Simple form	V-ing form
I couldn't buckle you couldn't buckle he couldn't buckle we couldn't buckle you couldn't buckle they couldn't buckle	I couldn't be buckling you couldn't be buckling he couldn't be buckling we couldn't be buckling you couldn't be buckling they couldn't be buckling
Perfect	V-ing perfect
I couldn't have buckled you couldn't have buckled he couldn't have buckled we couldn't have buckled you couldn't have buckled they couldn't have buckled	I couldn't have been buckling you couldn't have been buckling he couldn't have been buckling we couldn't have been buckling you couldn't have been buckling they couldn't have been buckling

Interrogative form

Simple form	V-ing form
could I buckle? could you buckle? could he buckle? could we buckle? could you buckle? could they buckle?	could I be buckling? could you be buckling? could he be buckling? could we be buckling? could you be buckling? could they be buckling?
Perfect	V-ing perfect
could I have buckled? could you have buckled? could he have buckled? could we have buckled? could you have buckled? could they have buckled?	could I have been buckling? could you have been buckling? could he have been buckling? could we have been buckling? could you have been buckling? could they have been buckling?

Interro-negative form

Simple form	V-ing form
couldn't I buckle? couldn't you buckle? couldn't he buckle? couldn't we buckle? couldn't you buckle? couldn't they buckle?	couldn't I be buckling? couldn't you be buckling? couldn't he be buckling? couldn't we be buckling? couldn't you be buckling? couldn't they be buckling?
Perfect	V-ing perfect
couldn't I have buckled? couldn't you have buckled? couldn't he have buckled? couldn't we have buckled? couldn't you have buckled? couldn't they have buckled?	couldn't I have been buckling? couldn't you have been buckling? couldn't he have been buckling? couldn't we have been buckling? couldn't you have been buckling? couldn't they have been buckling?