World War II Adolf Hitler's invasion of Poland in September,,1939,ignited(点燃)Vorld War Il.One by one,Europe's nations surrendered before Germany's mechanized armies.Only Britain held firm.While the Allies(同盟国)conferred(协商)，treachery (背叛)approached from the East..On December 7th,1941,the Japanese planes attacked Pearl Harbor.The next day,the United States entered the war.The war World War II Adolf Hitler's ______ of Poland in September, 1939, ignited (点燃) World War II. One by one, Europe's nations _________ before Germany's mechanized armies. Only Britain held firm. While the Allies (同盟国) conferred (协商), treachery (背叛) __________from the East. On December 7th, 1941, the Japanese planes attacked Pearl Harbor. The next day, the United States entered the war. The war invasion surrendered approached