As well

[Xinfu]

-John was not too certain about the thing __ __.

Could I use as well? If not, is it because of the existence of not?

[Rusty]

You may use 'as well'.
'At all' also fits, but has a different meaning, of course. You could use 'at least' or 'at most'. There are several possible answers, including 'on Monday'.
'Of course' also fits.


When linking two negative ideas together, you can't use 'as well'.

[Xinfu]

You may use 'as well'.

When linking two negative ideas together, you can't use 'as well'.

If we can use as well in my sentence, does it mean either?

[Rusty]

Yes, that is what it means.

[Xinfu]

Excellent answer. Thank you.