Thank you for providing these interesting examples. They provide some examples of subtle yet important variants of common words.Hello!
1. His great concern, and that of many founding members of PiS, was corruption. Scrupulously honest themselves (his brother Jaroslaw does not even have a bank account) the twins could hardly have been more different from the sleek cronies who populate large parts of the Polish political spectrum.
About the part beginning with the twins…, I understand as follows.
The twins were almost not different from the sleek cronies….. (a real event, or not?)
= The twins were almost the same as the sleek cronies…..
No, it is actually the opposite. They were totally different. It would be almost impossible, in fact, to be more different than they were. When you add "hardly" it effectively changes "could have been" to its opposite.
2. he advised the opposition trade union’s leaders in their talks with the communist boss-class.
Is it possible to use on instead of in?
If you change it to "on" you change the meaning. When you advise them "in their talks" you imply that you are present. When you advise them "on their talks" you imply that you are preparing them for what they will say when they are -- later -- in their talks. The difference is somewhat subtle, however, so in some circumstances you could use them almost interchangeably. I would stick with the usage that I have suggested.
3. A surprise victor in 2005, Lech Kaczynski proved an uneasy president. He looked nervous at public occasions.
Is it possible to use on instead of at?
You could get away with either. However, it would be more normal to say "on public occasions." We would tend to use "at" when speaking about what happens at a particular place, rather than public occasions in general.
1, 2, 3 from Lech Kaczynski, Apr 15th 2010 | From The Economist print edition
Please consider 1, 2, 3.
Thanks in advance