Usage of the verb may

[Nautica19]

"These jeans don't fit me."
"Go on a diet and they____________."
a. may as well
b. may just
c. just may (the correct answer)
may have

Why is 'c' the correct answer?
because the verb 'fit' can be implied and the adverb 'just' cannot be entered after the verb may???This question is from ECPE test (grammar section)

[Alan]

Hi,

I think that it is probably too great an assumption that 'fit' is implied in (b). After all it could be open to other possibilities - work - break and so on. By ending the response with 'may' it is clear that 'fit' is understood from the rest of the conversation.

Alan
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English as a Second Language
You can read my ESL story A day in the life of a stately home owner

[Nautica19]

Can you explain as well why the position of 'just' in this case?Is there a rule?I mean 'b' is completely wrong because just is in the end?

[Glitterfairy25]

The rule is that - in this case - the phrase must end in a verb (although I'm not sure why this is), so you could have either:

go on a diet and they just may

or

go on a diet and they may just fit.