Complex sentence: Jews from Poland, France, Germany, the Netherlands, Czechoslovakia and the Soviet Union, as well as the Soviet POWs, were transported to Sobibór by rail and suffocated in gas chambers fed by the exhaust of a large petrol engine.
Split into simpler sentences: Jews from Poland, France, Germany, the Netherlands, Czechoslovakia and the Soviet Union, as well as the Soviet POWs, were transported to Sobibór by rail. Most were suffocated in gas chambers fed by the exhaust of a large petrol engine.