Railway freight cars are used for the shipment of goods. There are open cars, flat cars, box cars and tank cars. The most common type of freight cars is __________. 铁路货车用于装运货物。有敞车、平车、箱式车和油罐车。最常见的货车类型是__________。
A、box car箱式车
B、open car 敞车
C、flat car平车