could trek
Regular verb: trek - trekked- trekked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could trek
you could trek
he could trek
we could trek
you could trek
they could trek 	I could be trekking
you could be trekking
he could be trekking
we could be trekking
you could be trekking
they could be trekking	I could have trekked
you could have trekked
he could have trekked
we could have trekked
you could have trekked
they could have trekked	I could have been trekking
you could have been trekking
he could have been trekking
we could have been trekking
you could have been trekking
they could have been trekking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not trek
you could not trek
he could not trek
we could not trek
you could not trek
they could not trek 	I could not be trekking
you could not be trekking
he could not be trekking
we could not be trekking
you could not be trekking
they could not be trekking	I could not have trekked
you could not have trekked
he could not have trekked
we could not have trekked
you could not have trekked
they could not have trekked	I could not have been trekking
you could not have been trekking
he could not have been trekking
we could not have been trekking
you could not have been trekking
they could not have been trekking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I trek?
could you trek?
could he trek?
could we trek?
could you trek?
could they trek? 	could I be trekking?
could you be trekking?
could he be trekking?
could we be trekking?
could you be trekking?
could they be trekking? 	could I have trekked?
could you have trekked?
could he have trekked?
could we have trekked?
could you have trekked?
could they have trekked? 	could I have been trekking?
could you have been trekking?
could he have been trekking?
could we have been trekking?
could you have been trekking?
could they have been trekking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not trek?
could you not trek?
could he not trek?
could we not trek?
could you not trek?
could they not trek? 	could I not be trekking?
could you not be trekking?
could he not be trekking?
could we not be trekking?
could you not be trekking?
could they not be trekking? 	could I not have trekked?
could you not have trekked?
could he not have trekked?
could we not have trekked?
could you not have trekked?
could they not have trekked? 	could I not have been trekking?
could you not have been trekking?
could he not have been trekking?
could we not have been trekking?
could you not have been trekking?
could they not have been trekking?