English verb conjugation
COULD THROB

Regular verb: throb - throbbed - throbbed

Affirmation

Simple form	V-ing form
I could throb you could throb she could throb we could throb you could throb they could throb	I could be throbbing you could be throbbing she could be throbbing we could be throbbing you could be throbbing they could be throbbing
Perfect	V-ing perfect
I could have throbbed you could have throbbed she could have throbbed we could have throbbed you could have throbbed they could have throbbed	I could have been throbbing you could have been throbbing she could have been throbbing we could have been throbbing you could have been throbbing they could have been throbbing

Negation

Simple form	V-ing form
I couldn't throb you couldn't throb she couldn't throb we couldn't throb you couldn't throb they couldn't throb	I couldn't be throbbing you couldn't be throbbing she couldn't be throbbing we couldn't be throbbing you couldn't be throbbing they couldn't be throbbing
Perfect	V-ing perfect
I couldn't have throbbed you couldn't have throbbed she couldn't have throbbed we couldn't have throbbed you couldn't have throbbed they couldn't have throbbed	I couldn't have been throbbing you couldn't have been throbbing she couldn't have been throbbing we couldn't have been throbbing you couldn't have been throbbing they couldn't have been throbbing

Interrogative form

Simple form	V-ing form
could I throb? could you throb? could she throb? could we throb? could you throb? could they throb?	could I be throbbing? could you be throbbing? could she be throbbing? could we be throbbing? could you be throbbing? could they be throbbing?
Perfect	V-ing perfect
could I have throbbed? could you have throbbed? could she have throbbed? could we have throbbed? could you have throbbed? could they have throbbed?	could I have been throbbing? could you have been throbbing? could she have been throbbing? could we have been throbbing? could you have been throbbing? could they have been throbbing?

Interro-negative form

Simple form	V-ing form
couldn't I throb? couldn't you throb? couldn't she throb? couldn't we throb? couldn't you throb? couldn't they throb?	couldn't I be throbbing? couldn't you be throbbing? couldn't she be throbbing? couldn't we be throbbing? couldn't you be throbbing? couldn't they be throbbing?
Perfect	V-ing perfect
couldn't I have throbbed? couldn't you have throbbed? couldn't she have throbbed? couldn't we have throbbed? couldn't you have throbbed? couldn't they have throbbed?	couldn't I have been throbbing? couldn't you have been throbbing? couldn't she have been throbbing? couldn't we have been throbbing? couldn't you have been throbbing? couldn't they have been throbbing?