could trip
Regular verb: trip - tripped- tripped

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could trip
you could trip
he could trip
we could trip
you could trip
they could trip 	I could be tripping
you could be tripping
he could be tripping
we could be tripping
you could be tripping
they could be tripping	I could have tripped
you could have tripped
he could have tripped
we could have tripped
you could have tripped
they could have tripped	I could have been tripping
you could have been tripping
he could have been tripping
we could have been tripping
you could have been tripping
they could have been tripping	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't trip
you couldn't trip
he couldn't trip
we couldn't trip
you couldn't trip
they couldn't trip 	I couldn't be tripping
you couldn't be tripping
he couldn't be tripping
we couldn't be tripping
you couldn't be tripping
they couldn't be tripping	I couldn't have tripped
you couldn't have tripped
he couldn't have tripped
we couldn't have tripped
you couldn't have tripped
they couldn't have tripped	I couldn't have been tripping
you couldn't have been tripping
he couldn't have been tripping
we couldn't have been tripping
you couldn't have been tripping
they couldn't have been tripping	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I trip?
could you trip?
could he trip?
could we trip?
could you trip?
could they trip? 	could I be tripping?
could you be tripping?
could he be tripping?
could we be tripping?
could you be tripping?
could they be tripping? 	could I have tripped?
could you have tripped?
could he have tripped?
could we have tripped?
could you have tripped?
could they have tripped? 	could I have been tripping?
could you have been tripping?
could he have been tripping?
could we have been tripping?
could you have been tripping?
could they have been tripping? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I trip?
couldn't you trip?
couldn't he trip?
couldn't we trip?
couldn't you trip?
couldn't they trip? 	couldn't I be tripping?
couldn't you be tripping?
couldn't he be tripping?
couldn't we be tripping?
couldn't you be tripping?
couldn't they be tripping? 	couldn't I have tripped?
couldn't you have tripped?
couldn't he have tripped?
couldn't we have tripped?
couldn't you have tripped?
couldn't they have tripped? 	couldn't I have been tripping?
couldn't you have been tripping?
couldn't he have been tripping?
couldn't we have been tripping?
couldn't you have been tripping?
couldn't they have been tripping?