[Grammar] Hypothetical situations in the present

[Svet_Lana]

1) What if pollution got so bad that the private ownership of cars was banned - what would happen?
2) What if pollution got so bad that the private ownership of cars would / could be banned - what would happen?

Is it possible to use "would/could" in the complex "if-clause" like in the 2nd sentence? Or only the past forms of verbs are correct (sentence # 1)?
Thank you in advance for your answer.

 

[jutfrank]

This is to all extents a second conditional sentence. The first sentence is correct because it includes past tense verb forms. The second sentence is not correct in any sense with those modals.

 

[MikeNewYork]

I prefer the subjunctive form "were" in the first sentence.

 

[Svet_Lana]

Thank you very much for you clear and helpful explanation. I have a better understanding of the issue now. Hope so ...;-)