Teacher Discussion Forums

I was asked the other day if it's ever possible to place not somewhere else in a sentence not only after the first auxiliary.

(1) He couldn't have come.
(2) He could haven't come.
(3) He could have not come.

What do you say?

José

1) Fine
2) Yuck
3) He (probably) came although he had the option/possibility not to i.e. not negates come, not could.