English verb conjugation
COULD SIGNAL

Regular verb: signal - signalled - signalled

Affirmation

Simple form	V-ing form
I could signal you could signal he could signal we could signal you could signal they could signal	I could be signalling you could be signalling he could be signalling we could be signalling you could be signalling they could be signalling
Perfect	V-ing perfect
I could have signalled you could have signalled he could have signalled we could have signalled you could have signalled they could have signalled	I could have been signalling you could have been signalling he could have been signalling we could have been signalling you could have been signalling they could have been signalling

Negation

Simple form	V-ing form
I couldn't signal you couldn't signal he couldn't signal we couldn't signal you couldn't signal they couldn't signal	I couldn't be signalling you couldn't be signalling he couldn't be signalling we couldn't be signalling you couldn't be signalling they couldn't be signalling
Perfect	V-ing perfect
I couldn't have signalled you couldn't have signalled he couldn't have signalled we couldn't have signalled you couldn't have signalled they couldn't have signalled	I couldn't have been signalling you couldn't have been signalling he couldn't have been signalling we couldn't have been signalling you couldn't have been signalling they couldn't have been signalling

Interrogative form

Simple form	V-ing form
could I signal? could you signal? could he signal? could we signal? could you signal? could they signal?	could I be signalling? could you be signalling? could he be signalling? could we be signalling? could you be signalling? could they be signalling?
Perfect	V-ing perfect
could I have signalled? could you have signalled? could he have signalled? could we have signalled? could you have signalled? could they have signalled?	could I have been signalling? could you have been signalling? could he have been signalling? could we have been signalling? could you have been signalling? could they have been signalling?

Interro-negative form

Simple form	V-ing form
couldn't I signal? couldn't you signal? couldn't he signal? couldn't we signal? couldn't you signal? couldn't they signal?	couldn't I be signalling? couldn't you be signalling? couldn't he be signalling? couldn't we be signalling? couldn't you be signalling? couldn't they be signalling?
Perfect	V-ing perfect
couldn't I have signalled? couldn't you have signalled? couldn't he have signalled? couldn't we have signalled? couldn't you have signalled? couldn't they have signalled?	couldn't I have been signalling? couldn't you have been signalling? couldn't he have been signalling? couldn't we have been signalling? couldn't you have been signalling? couldn't they have been signalling?