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I have seen the following paragraph in a sample IELTS writing test but don't understand its grammatical structure. Why is it in question format but affirmative?

To conclude, some say that we can get to know a country and its customs from the internet or TV, others believe that by going to those countries can we gain a deeper understanding.

marked as duplicate by Edwin Ashworth, Mari-Lou A, Skooba, user067531, jimm101 Feb 15 '18 at 19:25

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  • Does “By their works shall you know them” also confuse you, or does that one make sense? It's the same sort of inversion. – tchrist Feb 15 '18 at 3:21
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    The sentence is not idiomatic. If it was worded as "... believe that only by going ..." it would be idiomatic. – Hot Licks Feb 15 '18 at 3:25
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    Looks like someone left out an 'only': "others believe that only by going to those countries can we gain a deeper understanding." – Wayfaring Stranger Feb 15 '18 at 3:37
  • Yes; an 'only' makes semantic sense and is a necessary inversion-trigger here. – Edwin Ashworth Feb 15 '18 at 8:24

I agree that an "only" is missing from the example. As a native speaker the general rule here had me puzzled for a bit, and I tried to think of other examples where this inversion happens. Then I recalled some song lyrics from the musical "Oklahoma":

Never have I once looked back to sigh
Over the romance behind me
Many a new day will dawn
Before I do

Certain "negative" adverbials at the beginning of a sentence or phrase trigger the inversion of the usual order of subject and auxiliary verb. For example,

We can gain an understanding only by .... -> Only by ... can we gain an understanding.

You might want to check out this answer for a more complete explanation.

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