我国危险化学品的主安全标志有（）种。 ["14","16","11","17"]
冲压生产中预防废品的措施有哪些？
简述下级向上级领导汇报工作时应注意的礼仪。
公司将资金占用在应收账款上而放弃的投资于其他方面的收益，称为应收账款的（） ["管理成本","坏账成本","短缺成本","机会成本"]
According to the way the steering gear is operated, the steering gear may be divided into: hand - steering, （） and automatic steering. ["hydraulic steering","follow-up steering","remote control steering","air controlled steering"]
简述主席台就座者应注意的礼仪。
