English verb conjugation
COULD YELLOW

Regular verb: yellow - yellowed - yellowed

Affirmation

Simple form	V-ing form
I could yellow you could yellow she could yellow we could yellow you could yellow they could yellow	I could be yellowing you could be yellowing she could be yellowing we could be yellowing you could be yellowing they could be yellowing
Perfect	V-ing perfect
I could have yellowed you could have yellowed she could have yellowed we could have yellowed you could have yellowed they could have yellowed	I could have been yellowing you could have been yellowing she could have been yellowing we could have been yellowing you could have been yellowing they could have been yellowing

Negation

Simple form	V-ing form
I couldn't yellow you couldn't yellow she couldn't yellow we couldn't yellow you couldn't yellow they couldn't yellow	I couldn't be yellowing you couldn't be yellowing she couldn't be yellowing we couldn't be yellowing you couldn't be yellowing they couldn't be yellowing
Perfect	V-ing perfect
I couldn't have yellowed you couldn't have yellowed she couldn't have yellowed we couldn't have yellowed you couldn't have yellowed they couldn't have yellowed	I couldn't have been yellowing you couldn't have been yellowing she couldn't have been yellowing we couldn't have been yellowing you couldn't have been yellowing they couldn't have been yellowing

Interrogative form

Simple form	V-ing form
could I yellow? could you yellow? could she yellow? could we yellow? could you yellow? could they yellow?	could I be yellowing? could you be yellowing? could she be yellowing? could we be yellowing? could you be yellowing? could they be yellowing?
Perfect	V-ing perfect
could I have yellowed? could you have yellowed? could she have yellowed? could we have yellowed? could you have yellowed? could they have yellowed?	could I have been yellowing? could you have been yellowing? could she have been yellowing? could we have been yellowing? could you have been yellowing? could they have been yellowing?

Interro-negative form

Simple form	V-ing form
couldn't I yellow? couldn't you yellow? couldn't she yellow? couldn't we yellow? couldn't you yellow? couldn't they yellow?	couldn't I be yellowing? couldn't you be yellowing? couldn't she be yellowing? couldn't we be yellowing? couldn't you be yellowing? couldn't they be yellowing?
Perfect	V-ing perfect
couldn't I have yellowed? couldn't you have yellowed? couldn't she have yellowed? couldn't we have yellowed? couldn't you have yellowed? couldn't they have yellowed?	couldn't I have been yellowing? couldn't you have been yellowing? couldn't she have been yellowing? couldn't we have been yellowing? couldn't you have been yellowing? couldn't they have been yellowing?