They first came a long time ago
Ask this question again, you're going to need a more specific time the president has done this. however, if you are asking about WWI, the USS Lusitania, the Zimmerman Telegram, German U Boats targeting American ships, and so on.
Only adult male citizens of Athens who have completed their military training were allowed to vote in that city-state.
This obviously excluded boys, slaves, freed slaves, women, and people who were 'immigrants,' as well as former citizens of Athens. Athenian constitution was very rigid and didn't allow for any alterations for a very long time.
The farming market dried up
B - are too far apart
Conduction in fluids doesn't work as the molecules are loosely packed as opposed to conduction in solides where the molecules are tightly packed.