English verb conjugation
COULD BOIL

Regular verb: boil - boiled - boiled

Affirmation

Simple form	V-ing form
I could boil you could boil he could boil we could boil you could boil they could boil	I could be boiling you could be boiling he could be boiling we could be boiling you could be boiling they could be boiling
Perfect	V-ing perfect
I could have boiled you could have boiled he could have boiled we could have boiled you could have boiled they could have boiled	I could have been boiling you could have been boiling he could have been boiling we could have been boiling you could have been boiling they could have been boiling

Negation

Simple form	V-ing form
I couldn't boil you couldn't boil he couldn't boil we couldn't boil you couldn't boil they couldn't boil	I couldn't be boiling you couldn't be boiling he couldn't be boiling we couldn't be boiling you couldn't be boiling they couldn't be boiling
Perfect	V-ing perfect
I couldn't have boiled you couldn't have boiled he couldn't have boiled we couldn't have boiled you couldn't have boiled they couldn't have boiled	I couldn't have been boiling you couldn't have been boiling he couldn't have been boiling we couldn't have been boiling you couldn't have been boiling they couldn't have been boiling

Interrogative form

Simple form	V-ing form
could I boil? could you boil? could he boil? could we boil? could you boil? could they boil?	could I be boiling? could you be boiling? could he be boiling? could we be boiling? could you be boiling? could they be boiling?
Perfect	V-ing perfect
could I have boiled? could you have boiled? could he have boiled? could we have boiled? could you have boiled? could they have boiled?	could I have been boiling? could you have been boiling? could he have been boiling? could we have been boiling? could you have been boiling? could they have been boiling?

Interro-negative form

Simple form	V-ing form
couldn't I boil? couldn't you boil? couldn't he boil? couldn't we boil? couldn't you boil? couldn't they boil?	couldn't I be boiling? couldn't you be boiling? couldn't he be boiling? couldn't we be boiling? couldn't you be boiling? couldn't they be boiling?
Perfect	V-ing perfect
couldn't I have boiled? couldn't you have boiled? couldn't he have boiled? couldn't we have boiled? couldn't you have boiled? couldn't they have boiled?	couldn't I have been boiling? couldn't you have been boiling? couldn't he have been boiling? couldn't we have been boiling? couldn't you have been boiling? couldn't they have been boiling?