English verb conjugation
COULD ENTER

Regular verb: enter - entered - entered

Affirmation

Simple form	V-ing form
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
Perfect	V-ing perfect
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
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
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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
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?
Perfect	V-ing perfect
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?