工程签证是工程承包双方在施工过程中按合同约定对顺延工期、()等所达成的双方意思表示一致的补充协议。
A、支付各种费用
B、回访与保修
C、不合格品的处理
D、物资采购
参考答案:A
_____in the queue for half an hour, Tom suddenly realized that he had left his wallet at home. [ ]
A. Waiting
B. Have waited
C. Having waited
D. Waited
PGM-48钢轨打磨车的走行系统液压油冷却风扇有()冷却速度。