检验人员应将所抽的平均样品在抽样后( )内送到检验室。
A．12小时 B．24小时 C．28小时 D．30小时
参考答案：B
Jack hurt his leg yesterday. Now he is in the hospital. ____________
A. It’s my pleasure. B. All right. C. I’m sorry to hear that.
气动调节阀有哪两种执行机构？
