On no condition should they swim at night.

[Nonverbis]

The book: English. Theory and Practice. Inversion by Richard Grant.

This is the answer key to an exercise whose task was to find correct cases of inversion.

I suppose, 8th is correct. Could you tell me whether the answer key is wrong here?

 

[jutfrank]

Yes, 8 involves inversion (should they).

It seems this book has a lot of errors.

 

[5jj]

On no condition should they swim at night is not a correct English sentence. It would make sense if the words i've underlined were In no circumstances.

 

[Nonverbis]

On no condition should they swim at night is not a correct English sentence.

Could you clarify why it is erroneous?



Taken from here: https://www.oxfordlearnersdictionaries.com/definition/english/condition_1?q=condition

 

[jutfrank]

On no condition should they swim at night is not a correct English sentence. It would make sense if the words i've underlined were In no circumstances.

I take your point, but I think it's just about okay.

Still, under no circumstances is much better.

 

[Skrej]

With the change form 'on' to 'under', it works in AmE (as also noted in the dictionary entry'. I'd expect to see the plural form of 'conditions', though.