what does "across" mean in "The North Korean-Chinese border stretches 880 miles, across China's Lia"
what does "across" mean in "The North Korean-Chinese border stretches 880 miles, across China's Liaoning Province"?
Because BOTH China's Liaoning province and Jilin Province are on the border with North Korea, what does it by "across" Liaoning?

Also, I should say:
1) defense in the northern border? or
2)defense for the northern border? or
3) desense of the northern border?

Question

what does "across" mean in "The North Korean-Chinese border stretches 880 miles, across China's Lia"
what does "across" mean in "The North Korean-Chinese border stretches 880 miles, across China's Liaoning Province"?
Because BOTH China's Liaoning province and Jilin Province are on the border with North Korea, what does it by "across" Liaoning?

Also, I should say:
1) defense in the northern border?  or
2)defense for the northern border? or
3) desense of the northern border?

Answer

across in this context means the total stretch of land that meets at the Liaoning province and North Korea. The area where both of those territories share the border.

And all three of the sentence structures work, it depends on what meaning you are trying to convey that will affect your choice of preposition. I hope this helps...

Answer

'across' normally suggests 'horizontally' - so here it would mean 'from one side of Liaoning to the other'. I think it's a little strange to refer to a north-south border to be called 'across'.
Apart from that, it's correct. They are talking about Liaoning specifically, not the border. I guess that that would be clearer from the context.
3: of the.

Answer

In this context, it means the the Liaoning Province is on the border with North Korea. Also, the third option "defense of the Northern border" is best.

Non perdere l'opportunità di imparare una lingua comodamente da casa tua. Esplora la nostra selezione di insegnanti di lingue esperti e iscriviti subito alla tua prima lezione!