The factory has _____ workers due to the drop in sales, which will lead to an increase in unemployment.

A．paid off

B．laid off

C．set off

D．put off

急性血源性骨髓炎最常见的致病菌是()

A．白色葡萄球菌

B．乙型溶血性链球菌

C．溶血性金黄色葡萄球菌

D．大肠埃希菌

E．肺炎链球菌