What were the twenty nations that belonged to the allied powers?

The US, UK, France, Australia, Soviet Union, Belgium, Brazil, Canada, China, Denmark, Greece, Netherlands, New Zealand, Norway, Poland, South Africa, Yugoslavia. That's only 17. I don't know the last three.

The US, UK, France, Australia, Soviet Union, Belgium, Brazil, Canada, China, Denmark, Greece, Netherlands, New Zealand, Norway, Poland, South Africa, Yugoslavia Germany, Austria-Hungary, and Turkey

Basically create a schedule on what you need to study and stick with it