The main purpose of the text is to 
Saudi Arabia and Iran are mentioned in paragraphs 2 and 3 (lines 8-20) because they 
In the fragment “The threat to stability is all the greater given that Iran is likely to win any such clash and to treat the result as a licence to reassert its influence in the region” (lines 17-20), given that can be replaced, without change in meaning, by 
The production of oil from shale rock in the US is mentioned in paragraph 4 (lines 21-29) because in 2018 it 
The phrase that shift (line 46) refers to the change in China from a 
In the fragments “some recent data suggests that as economic growth has picked up” (lines 47-48) and “Beijing has high ambitions for a much cleaner energy economy, driven not least by the levels of air pollution in many of the major cities” (lines 49-51), picked up and driven by mean, respectively, 
In terms of numerical reference, one concludes that 
Concerning the renewable energy industry, the author affirms that it 
According to the last paragraph, the author believes that the 
In the phrase “with many others carelessly throwing food away” the phrasal verb throwing food away could be replaced by 