could brief
Regular verb: brief - briefed- briefed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could brief
you could brief
he could brief
we could brief
you could brief
they could brief 	I could be briefing
you could be briefing
he could be briefing
we could be briefing
you could be briefing
they could be briefing	I could have briefed
you could have briefed
he could have briefed
we could have briefed
you could have briefed
they could have briefed	I could have been briefing
you could have been briefing
he could have been briefing
we could have been briefing
you could have been briefing
they could have been briefing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't brief
you couldn't brief
he couldn't brief
we couldn't brief
you couldn't brief
they couldn't brief 	I couldn't be briefing
you couldn't be briefing
he couldn't be briefing
we couldn't be briefing
you couldn't be briefing
they couldn't be briefing	I couldn't have briefed
you couldn't have briefed
he couldn't have briefed
we couldn't have briefed
you couldn't have briefed
they couldn't have briefed	I couldn't have been briefing
you couldn't have been briefing
he couldn't have been briefing
we couldn't have been briefing
you couldn't have been briefing
they couldn't have been briefing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I brief?
could you brief?
could he brief?
could we brief?
could you brief?
could they brief? 	could I be briefing?
could you be briefing?
could he be briefing?
could we be briefing?
could you be briefing?
could they be briefing? 	could I have briefed?
could you have briefed?
could he have briefed?
could we have briefed?
could you have briefed?
could they have briefed? 	could I have been briefing?
could you have been briefing?
could he have been briefing?
could we have been briefing?
could you have been briefing?
could they have been briefing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I brief?
couldn't you brief?
couldn't he brief?
couldn't we brief?
couldn't you brief?
couldn't they brief? 	couldn't I be briefing?
couldn't you be briefing?
couldn't he be briefing?
couldn't we be briefing?
couldn't you be briefing?
couldn't they be briefing? 	couldn't I have briefed?
couldn't you have briefed?
couldn't he have briefed?
couldn't we have briefed?
couldn't you have briefed?
couldn't they have briefed? 	couldn't I have been briefing?
couldn't you have been briefing?
couldn't he have been briefing?
couldn't we have been briefing?
couldn't you have been briefing?
couldn't they have been briefing?