could enter
Regular verb: enter - entered- entered

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could enter
you could enter
he could enter
we could enter
you could enter
they could enter 	I could be entering
you could be entering
he could be entering
we could be entering
you could be entering
they could be entering	I could have entered
you could have entered
he could have entered
we could have entered
you could have entered
they could have entered	I could have been entering
you could have been entering
he could have been entering
we could have been entering
you could have been entering
they could have been entering	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't enter
you couldn't enter
he couldn't enter
we couldn't enter
you couldn't enter
they couldn't enter 	I couldn't be entering
you couldn't be entering
he couldn't be entering
we couldn't be entering
you couldn't be entering
they couldn't be entering	I couldn't have entered
you couldn't have entered
he couldn't have entered
we couldn't have entered
you couldn't have entered
they couldn't have entered	I couldn't have been entering
you couldn't have been entering
he couldn't have been entering
we couldn't have been entering
you couldn't have been entering
they couldn't have been entering	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I enter?
could you enter?
could he enter?
could we enter?
could you enter?
could they enter? 	could I be entering?
could you be entering?
could he be entering?
could we be entering?
could you be entering?
could they be entering? 	could I have entered?
could you have entered?
could he have entered?
could we have entered?
could you have entered?
could they have entered? 	could I have been entering?
could you have been entering?
could he have been entering?
could we have been entering?
could you have been entering?
could they have been entering? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I enter?
couldn't you enter?
couldn't he enter?
couldn't we enter?
couldn't you enter?
couldn't they enter? 	couldn't I be entering?
couldn't you be entering?
couldn't he be entering?
couldn't we be entering?
couldn't you be entering?
couldn't they be entering? 	couldn't I have entered?
couldn't you have entered?
couldn't he have entered?
couldn't we have entered?
couldn't you have entered?
couldn't they have entered? 	couldn't I have been entering?
couldn't you have been entering?
couldn't he have been entering?
couldn't we have been entering?
couldn't you have been entering?
couldn't they have been entering?