Cold weather is the best answer!
a) - Poland was also at war with the Soviet, unlikely it would help
b) Soviet Union has only very limited access to the Mediterranean, which likely was completly cut off at the time anyway
c) they could have it, but China was too busy fighting its own war!
They believe that they would be ignored if representation was based on population while large states, because they will not have the same advantages that the big states have.
