Article

Today scientists in several countries - particularly … United States, Britain and Russia - are working out … theory behind machines that may break down the language barrier between nations.

(a) the/the
(b) the/-
© -/-
(d) -/the

Many learners, I think, know without difficulty that the definite article is used before “United States”. So, © and (d) are both incorrect.

 As for the other options, I do not know exactly which one is correct?
 
   Please, could you help me?

Since it was defined as “theory…that may break down…” I would use ‘the’.
Still I didn’t get the ‘theory behind machines’ expression…

Hi Foreigner!

I’d go with (a) the/the. We need the definite article twice in this sentence.

As you said “the” is used before “United States”. We’re also talking about a specific theory, therefore we need “the” once again.

The expression “the theory behind something” means the ideas or principles behind something.

Hope this helps!
Regards

Very good.
And how would you explain that “ideas or principles behind machines” in plain words?

Thank you Eugene!
Regarding your last question:

Today scientists in several countries - particularly the United States, Britain and Russia - are working out the theory behind machines that may break down the language barrier between nations.

In this sentence the phrase in bold can be substituted by: Today scientists in several countries, particularly the United States, Britain and Russia, are developing/planning the ideas/theories/principles connected with the machines that may break down the language barrier between nations.

Basically, the scientists are trying to develop or create those “machines that may break down the language barrier between nations”.

I hope this answers your question!

We can also see if others agree. After all, this is my personal interpretation.

Regards

Thank you for the explanation, Stoyan.
To me ‘the theory behind machines’ still sounds like as if machines possessed some ideas/principles and plotted against humans. Plain ‘…the theory how machines could break down the language barrier between nations’ would remove all my doubts…

 Hi Eugene,

I have found the site on the Net that may interest you and answer your query.

 For more information you can visit the following link:

 [blog.modernmechanix.com/breaking ... e-barrier/](http://blog.modernmechanix.com/breaking-the-language-barrier/)

Hi Foreigner,
I’ve found the excerpt in the article, if it was what you pointed to.
Written in 1958, the phrase may have excited a reader (or the author), but I’m digging in my heels and not going to applaud the author for putting things like he did.


“Any fool can make things bigger, more complex, and more violent. it takes… a lot of courage–to move in the opposite direction.”