I could quote you could quote he could quote we could quote you could quote they could quote
V-ing form
I could be quoting you could be quoting he could be quoting we could be quoting you could be quoting they could be quoting
Perfect
I could have quoted you could have quoted he could have quoted we could have quoted you could have quoted they could have quoted
V-ing perfect
I could have been quoting you could have been quoting he could have been quoting we could have been quoting you could have been quoting they could have been quoting
Negation
Simple form
I couldn't quote you couldn't quote he couldn't quote we couldn't quote you couldn't quote they couldn't quote
V-ing form
I couldn't be quoting you couldn't be quoting he couldn't be quoting we couldn't be quoting you couldn't be quoting they couldn't be quoting
Perfect
I couldn't have quoted you couldn't have quoted he couldn't have quoted we couldn't have quoted you couldn't have quoted they couldn't have quoted
V-ing perfect
I couldn't have been quoting you couldn't have been quoting he couldn't have been quoting we couldn't have been quoting you couldn't have been quoting they couldn't have been quoting
Interrogative form
Simple form
could I quote? could you quote? could he quote? could we quote? could you quote? could they quote?
V-ing form
could I be quoting? could you be quoting? could he be quoting? could we be quoting? could you be quoting? could they be quoting?
Perfect
could I have quoted? could you have quoted? could he have quoted? could we have quoted? could you have quoted? could they have quoted?
V-ing perfect
could I have been quoting? could you have been quoting? could he have been quoting? could we have been quoting? could you have been quoting? could they have been quoting?
Interro-negative form
Simple form
couldn't I quote? couldn't you quote? couldn't he quote? couldn't we quote? couldn't you quote? couldn't they quote?
V-ing form
couldn't I be quoting? couldn't you be quoting? couldn't he be quoting? couldn't we be quoting? couldn't you be quoting? couldn't they be quoting?
Perfect
couldn't I have quoted? couldn't you have quoted? couldn't he have quoted? couldn't we have quoted? couldn't you have quoted? couldn't they have quoted?
V-ing perfect
couldn't I have been quoting? couldn't you have been quoting? couldn't he have been quoting? couldn't we have been quoting? couldn't you have been quoting? couldn't they have been quoting?