在用双相滴定法测定苯甲酸钠的含量时，用乙醚萃取的物质是
A．苯甲酸钠B．苯甲酸C．甲基橙D．盐酸E．氯化钠
参考答案：B
— What do you think we can do for our aged parents?
— You _____ do anything except to be with them and be yourself. [ ]
A. don't have to
B. oughtn't to
C. mustn't
D. can't
获得《出口危险货物包装容器质量许可证》的企业半年内检验累计批次合格率低于80%者，或连续二次抽样检验不合格，限期改进后达到标准要求的由发证机关吊销其质量许可证。( )
