I could elapse you could elapse she could elapse we could elapse you could elapse they could elapse
V-ing form
I could be elapsing you could be elapsing she could be elapsing we could be elapsing you could be elapsing they could be elapsing
Perfect
I could have elapsed you could have elapsed she could have elapsed we could have elapsed you could have elapsed they could have elapsed
V-ing perfect
I could have been elapsing you could have been elapsing she could have been elapsing we could have been elapsing you could have been elapsing they could have been elapsing
Negation
Simple form
I couldn't elapse you couldn't elapse she couldn't elapse we couldn't elapse you couldn't elapse they couldn't elapse
V-ing form
I couldn't be elapsing you couldn't be elapsing she couldn't be elapsing we couldn't be elapsing you couldn't be elapsing they couldn't be elapsing
Perfect
I couldn't have elapsed you couldn't have elapsed she couldn't have elapsed we couldn't have elapsed you couldn't have elapsed they couldn't have elapsed
V-ing perfect
I couldn't have been elapsing you couldn't have been elapsing she couldn't have been elapsing we couldn't have been elapsing you couldn't have been elapsing they couldn't have been elapsing
Interrogative form
Simple form
could I elapse? could you elapse? could she elapse? could we elapse? could you elapse? could they elapse?
V-ing form
could I be elapsing? could you be elapsing? could she be elapsing? could we be elapsing? could you be elapsing? could they be elapsing?
Perfect
could I have elapsed? could you have elapsed? could she have elapsed? could we have elapsed? could you have elapsed? could they have elapsed?
V-ing perfect
could I have been elapsing? could you have been elapsing? could she have been elapsing? could we have been elapsing? could you have been elapsing? could they have been elapsing?
Interro-negative form
Simple form
couldn't I elapse? couldn't you elapse? couldn't she elapse? couldn't we elapse? couldn't you elapse? couldn't they elapse?
V-ing form
couldn't I be elapsing? couldn't you be elapsing? couldn't she be elapsing? couldn't we be elapsing? couldn't you be elapsing? couldn't they be elapsing?
Perfect
couldn't I have elapsed? couldn't you have elapsed? couldn't she have elapsed? couldn't we have elapsed? couldn't you have elapsed? couldn't they have elapsed?
V-ing perfect
couldn't I have been elapsing? couldn't you have been elapsing? couldn't she have been elapsing? couldn't we have been elapsing? couldn't you have been elapsing? couldn't they have been elapsing?