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We ought to avoid littering lest we might/should pollute the city.

We ought to avoid littering for fear that we might/should pollute the city.

Do both might and should fit in the above samples? Thanks.
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Should fits, as the BrE alternative to the subjunctive, in the first sentence, but not might.

lest we pollute /should pollute the city.

I don't think that for fear that need take the subjunctive...but I haven't tried to look it up.
Comments  
Mister MicawberShould fits, as the BrE alternative to the subjunctive, in the first sentence, but not might.

lest we pollute /should pollute the city.

I don't think that for fear that need take the subjunctive...but I haven't tried to look it up.

Thanks, Mister.