English verb conjugation
COULD TEST

Regular verb: test - tested - tested

Affirmation

Simple form	V-ing form
I could test you could test he could test we could test you could test they could test	I could be testing you could be testing he could be testing we could be testing you could be testing they could be testing
Perfect	V-ing perfect
I could have tested you could have tested he could have tested we could have tested you could have tested they could have tested	I could have been testing you could have been testing he could have been testing we could have been testing you could have been testing they could have been testing

Negation

Simple form	V-ing form
I couldn't test you couldn't test he couldn't test we couldn't test you couldn't test they couldn't test	I couldn't be testing you couldn't be testing he couldn't be testing we couldn't be testing you couldn't be testing they couldn't be testing
Perfect	V-ing perfect
I couldn't have tested you couldn't have tested he couldn't have tested we couldn't have tested you couldn't have tested they couldn't have tested	I couldn't have been testing you couldn't have been testing he couldn't have been testing we couldn't have been testing you couldn't have been testing they couldn't have been testing

Interrogative form

Simple form	V-ing form
could I test? could you test? could he test? could we test? could you test? could they test?	could I be testing? could you be testing? could he be testing? could we be testing? could you be testing? could they be testing?
Perfect	V-ing perfect
could I have tested? could you have tested? could he have tested? could we have tested? could you have tested? could they have tested?	could I have been testing? could you have been testing? could he have been testing? could we have been testing? could you have been testing? could they have been testing?

Interro-negative form

Simple form	V-ing form
couldn't I test? couldn't you test? couldn't he test? couldn't we test? couldn't you test? couldn't they test?	couldn't I be testing? couldn't you be testing? couldn't he be testing? couldn't we be testing? couldn't you be testing? couldn't they be testing?
Perfect	V-ing perfect
couldn't I have tested? couldn't you have tested? couldn't he have tested? couldn't we have tested? couldn't you have tested? couldn't they have tested?	couldn't I have been testing? couldn't you have been testing? couldn't he have been testing? couldn't we have been testing? couldn't you have been testing? couldn't they have been testing?