If you’re talking about line breaks that are created automatically by Word
as part of the text justification process (i.e., because the text reached the right margin),
then I doubt that this will be possible.
But I suspect that this isn’t really your problem; I suspect that your problem is
How do I get expressions containing minus signs, including superscripted ones, e.g.,
The quick brown fox jumps at 10 cm s-1 over the lazy dog.
not to break at the right margin, as if the minus sign were a hyphen:
blah blah blah blah blah blah blah blah … The quick brown fox jumps at 10 cm s-
1 over the lazy dog.
and, if that’s your problem,
then see Preventing line breaks in superscript.
Specifically, I recommend the Ctrl+Shift+- answer.
If you have a large document, you’ll probably want to do a “Find and Replace”,
replacing superscripted hyphens with non-breaking hyphens (using the