can't only

[azz]

a. I don't only teach French. I teach math as well.
b. I can't only teach French. I can teach math as well.

I think (a) works, and (b) does not.

However these two seem fine to me

c. I can't only teach my students French. I have to teach them math as well.
d. I can't just teach my students French. I have to teach them math as well.


Would you say that I am correct?
Is (b) wrong?
Are (c) and (d) grammatically sound?

How about
e. I can't only play the guitar. I have to sing as well. (that's what expected of me)
f. He can't only type. He has to speak the words he is typing as well.
(he's a weird person!)
?

Many thanks

[tony h]

Well the obvious thing is that they are all wrong. It is maths, or in my old world math's, not math. Mathematics is a plural, collective term.


I wait to be shot down by Erik and Phil

[Phil White]

Your intuition is correct. b) does not work. The rest do, some better than others. c), e) and f) would all sound better with "just" in place of "only".

I find it difficult to explain exactly why b) does not work, but here is an attempt. The basis of the statement in b) is the "not only ... but also ..." construction. If we expand the "can't" in sentence b) so that the "not only" appears correctly, the sentence suddenly works:

"I can not only teach French. I can teach math as well."

It works even better in a couple of other forms:
"I can teach not only French but also math."
"Not only can I teach French; I can also teach math."

In this sentence, you are not actually negating the "can". You are not saying that there is a circumstance in which I cannot teach French. Thus, the "can" should not be negated in the form "cannot" or "can't".

In all the other sentences you are saying that there are situations in which something is impossible or not permitted. Thus, the "can" should be negated.

I hope that makes some sense!

And yes, in the UK, we use "maths" and not "math". In the US, the term "math" is used. Horrid!