English verb conjugation
COULD TREMBLE

Regular verb: tremble - trembled - trembled

Affirmation

Simple form	V-ing form
I could tremble you could tremble he could tremble we could tremble you could tremble they could tremble	I could be trembling you could be trembling he could be trembling we could be trembling you could be trembling they could be trembling
Perfect	V-ing perfect
I could have trembled you could have trembled he could have trembled we could have trembled you could have trembled they could have trembled	I could have been trembling you could have been trembling he could have been trembling we could have been trembling you could have been trembling they could have been trembling

Negation

Simple form	V-ing form
I couldn't tremble you couldn't tremble he couldn't tremble we couldn't tremble you couldn't tremble they couldn't tremble	I couldn't be trembling you couldn't be trembling he couldn't be trembling we couldn't be trembling you couldn't be trembling they couldn't be trembling
Perfect	V-ing perfect
I couldn't have trembled you couldn't have trembled he couldn't have trembled we couldn't have trembled you couldn't have trembled they couldn't have trembled	I couldn't have been trembling you couldn't have been trembling he couldn't have been trembling we couldn't have been trembling you couldn't have been trembling they couldn't have been trembling

Interrogative form

Simple form	V-ing form
could I tremble? could you tremble? could he tremble? could we tremble? could you tremble? could they tremble?	could I be trembling? could you be trembling? could he be trembling? could we be trembling? could you be trembling? could they be trembling?
Perfect	V-ing perfect
could I have trembled? could you have trembled? could he have trembled? could we have trembled? could you have trembled? could they have trembled?	could I have been trembling? could you have been trembling? could he have been trembling? could we have been trembling? could you have been trembling? could they have been trembling?

Interro-negative form

Simple form	V-ing form
couldn't I tremble? couldn't you tremble? couldn't he tremble? couldn't we tremble? couldn't you tremble? couldn't they tremble?	couldn't I be trembling? couldn't you be trembling? couldn't he be trembling? couldn't we be trembling? couldn't you be trembling? couldn't they be trembling?
Perfect	V-ing perfect
couldn't I have trembled? couldn't you have trembled? couldn't he have trembled? couldn't we have trembled? couldn't you have trembled? couldn't they have trembled?	couldn't I have been trembling? couldn't you have been trembling? couldn't he have been trembling? couldn't we have been trembling? couldn't you have been trembling? couldn't they have been trembling?