To celebrate the centennial of the founding of our country, the Central Bank especially issued a set of memorial coins.为了庆祝建国百年，中央银行特别发行了一套纪念币。They ran a sales promotion scheme in which a World Cup coin was given away with every four gallons of petrol purchased.他们正在搞促销活动，每购买四加仑汽油便可获赠一枚世界杯纪念币。