Task: Question Generation
Input (English): At the start of the war on 1 September 1939, the Allies consisted of France, Poland and the United Kingdom, as well as their dependent states, such as British India. Within days they were joined by the independent Dominions of the British Commonwealth: Australia, Canada, New Zealand and South Africa. After the start of the German invasion of North Europe until the Balkan Campaign, the Netherlands, Belgium, Greece, and Yugoslavia joined the Allies. After first having cooperated with Germany in invading Poland whilst remaining neutral in the Allied-Axis conflict, the Soviet Union perforce joined the Allies in June 1941 after being invaded by Germany. The United States provided war materiel and money all along, and officially joined in December 1941 after the Japanese attack on Pearl Harbor. China had already been in a prolonged war with Japan since the Marco Polo Bridge Incident of 1937, but officially joined the Allies in 1941.
Output (English): was the soviet union an ally in ww2?