English verb conjugation
COULD LOCK

Regular verb: lock - locked - locked

Affirmation

Simple form	V-ing form
I could lock you could lock she could lock we could lock you could lock they could lock	I could be locking you could be locking she could be locking we could be locking you could be locking they could be locking
Perfect	V-ing perfect
I could have locked you could have locked she could have locked we could have locked you could have locked they could have locked	I could have been locking you could have been locking she could have been locking we could have been locking you could have been locking they could have been locking

Negation

Simple form	V-ing form
I couldn't lock you couldn't lock she couldn't lock we couldn't lock you couldn't lock they couldn't lock	I couldn't be locking you couldn't be locking she couldn't be locking we couldn't be locking you couldn't be locking they couldn't be locking
Perfect	V-ing perfect
I couldn't have locked you couldn't have locked she couldn't have locked we couldn't have locked you couldn't have locked they couldn't have locked	I couldn't have been locking you couldn't have been locking she couldn't have been locking we couldn't have been locking you couldn't have been locking they couldn't have been locking

Interrogative form

Simple form	V-ing form
could I lock? could you lock? could she lock? could we lock? could you lock? could they lock?	could I be locking? could you be locking? could she be locking? could we be locking? could you be locking? could they be locking?
Perfect	V-ing perfect
could I have locked? could you have locked? could she have locked? could we have locked? could you have locked? could they have locked?	could I have been locking? could you have been locking? could she have been locking? could we have been locking? could you have been locking? could they have been locking?

Interro-negative form

Simple form	V-ing form
couldn't I lock? couldn't you lock? couldn't she lock? couldn't we lock? couldn't you lock? couldn't they lock?	couldn't I be locking? couldn't you be locking? couldn't she be locking? couldn't we be locking? couldn't you be locking? couldn't they be locking?
Perfect	V-ing perfect
couldn't I have locked? couldn't you have locked? couldn't she have locked? couldn't we have locked? couldn't you have locked? couldn't they have locked?	couldn't I have been locking? couldn't you have been locking? couldn't she have been locking? couldn't we have been locking? couldn't you have been locking? couldn't they have been locking?